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First of all I must warn you of the dangers bench grinders can represent. Here in Britain no one connected with a business is allowed to carry out any maintenance on any none-portable grinding machine unless they have attended and passed a course on the subject and every employer must keep a register recording what maintenance has been carried out and by whom. Grinding machines have been responsible for many industrial "accidents".
Householders and private individuals are exempt from the Law but cannot afford to be less well informed even though the five and six inch bench grinders sold to the domestic user represent a somewhat reduced risk, great care and precautions are still required, not the least of which is the use of good eye protection even if the grinder is fitted with shields.
The first problem about dressing the grinding wheel of a grinder intended for the domestic market is the tool rests are usually too small and insubstantial for the vibrating star-wheel type wheel dressing tool to be used correctly.
A demonstration would be the best way to learn how to dress a grinding wheel and there are many available on Youtube and here is a link to a particularly good video.
Finally, it is best to be aware of one little thought about problem. There is an optimum speed range when a grinding wheel works efficiently and small domestic grinders barely turn fast enough for them to be properly efficient, probably because it is reckoned price and user safety takes priority over efficiency.
The speed that is of concern is the surface or peripheral speed of the grinding surface rather than the rpm of the spindle and should that speed fall too low the wheel will not be able to operate efficiently, will become dull more quickly with a greater tendency to clog and the wheel will become hot in use and hot grinding wheels soon become dangerous.
I hope you will be able to see that by reducing the diameter of a grinding wheel by dressing it also reduces the surface speed of the grinding surface even though the spindle speed remains the same. The relationship between surface speed and spindle speed is why small grinding points need to spin at 20,000 rpm and an eight foot wheel at just a few hundred rpm - in both cases the surface speed is similar.
A domestic grinder should not be used for heavy work but as the size of the wheel is reduced it should be used only for increasingly light work and if it is desired to carry out "normal" grinding operations it would be better to replace the wheel sooner rather than later.
It should rotate freely, but it should feel like it's turning gears on the inside of the grinder. It should NOT be floppy, and it should NOT spin as if it's not turning gears inside the grinder. It should run straight and true.
It's possible that you didn't remember to install the inner (backup) arbor washer before installing the wheel. If you do that, the wheel will spin completely freely on the arbor shaft. Find that washer and install it under the wheel.
It's also possible that you installed a very thin cutoff wheel but your grinder won't accept one, that it requires a full-thickness grinding wheel. Some grinders won't grip a very thin cutoff wheel correctly.
You will need to pull the grinder apart & clean it out. Most likely cause of the grinder blocking up is a leak somewhere inside the machine dampening the grounds as they exit the grinder. They bind up, won't fall out and there is your blockage. You will need to find and fix the leak, there are many, many places for the leak to be, it's a job for a Krups Service Agent. I have outer housings with cutouts in them so I can run them and look inside at the same time to find those troublesome leaks.
Yes, the wobble can be fixed. First, remove both wheels and check the shaft bearings/bushings for wear. Make certain the grinder is unplugged and mounted securely. Try moving the shafts up, down side to side; there should be little or no noticeable movement. If there is movement it is a major(time and money) problem. I'm not familiar with what the shafts ride on. It could be, ball bearings(the best-long lasting, least friction, most accurate, but expensive), sealed bearings(almost as good as ball bearings, with many of the same attributes) and bushings(least expensive to produce and fit and cause the most friction. If excessive up,down side to side movement is present a decision must be made as to how much money/time you want to invest. If the shaft exhibit little movement; check if the shaft is running true/straight. Turn the grinder by hand while observing the shaft for bends. If none are seen by eye use a magnetic base micrometer to check run out(deviation from straight). If a micrometer isn't available; bend a short length of wire(coat hanger works nicely) with a small hook on one end and then put a pointer end on the other. Put a screw thought the end with the hook to mount it to the base of the grinder. Then bend the pointed end so it just touches the shaft. Rotate the shaft and notice if the distance changes between the point of the wire and the grinder shaft. Repeat for the other side. A couple of thousands won't hurt. However, any more and the cost effectiveness of tearing the grinder apart straightening the shaft must be considered. The most common cause of grinding wheel wobble is the wheels becoming out of true and/or unbalanced. This is easily cured with a wheel dressiing tool. The tool grinds the wheels in place. By gringing the wheels on the grinder they balance the wheel, true the wheel to the shaft and clean it of imbeded soft materials, aluminum, wood and so forth.
Lay it on its side and lean on it while you're holding the spindle lock button in- if you're right handed lay it on its right side with its back to you. Lay your elbow wherever you can on the handle once you get the button pushed and use your right hand for the wrench. If it's in the position I mention you'll push the wrench down to remove the wheel.
You can heat the center of the wheel, the metal part, to expand it a little.. makes it easier to get off sometimes.
The trick is to put the wheel on properly. Put a little NevrSeize on the spindle threads and screw the wheel on. Don't go picking up the grinder and hitting the switch because that will hammer that wheel on. Just screw it on and tighten fairly firmly.It only has to be tight enough to seat well on the spindle- it only turns one way, so as long as the wheel doesn't come off when it's coasting down it's tight enough.
Wear your safety glasses when grinding, them darn sparks are bad for your eyes.
This is a set screw. You need to take this out.
You can access this to either clean the burr
grinding wheel. Maybe this needs changed.
If you google the Kitchenaid A-9 Burr grinder you can get instructions to download on this machine.