I am using a this jigsaw and the motor keeps running whether i am holding down the button or not is this normal??

Use a straight edge guide. Clamp it on the work so the jigsaw can run against it. Be patient and go very slowly.

Motor is heating up because too much power is entering the unit. That will happen when the motor is NOT spinning at correct speed. This can be accounted for by using it for a job it was not untended for or excessive friction in the motor bearings.

You may have already permanently damaged the windings where on some of them the plastic insulation has melted and the wires now touch each other resulting in a lower than normal resistance, more current consumption and less back emf.

Unless that motor is binding, I believe you have damaged the motor - cannot be fixed but only replaced. Sorry.

It may be the centrifugal switch on the motor. The push button starts the motor and as the motor spins up to speed the centrifugal switch closes to keep the motor running. Hope this helps.

Press and hold the power button for fifteen seconds or so. If it prompts whether you want to shut down, ignore it and keep the power button pressed until it shuts off. Release the button, then press and hold for a second or two until it starts to reboot. Does it reboot and operate normally now?

that reset is for the high pressure switch. this means your compressor is getting to hot which is then increasing the pressure and tripping the switch because the fan isn't running. usually if a capacitor is bad you can give the motor a "kick start " and the blade will then start turning. use a long stick or screwdriver to spin the blade but then you will know you need a cap. that switch is protecting your compressor, don't hold it down to keep it running.

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get a nail file and sharpen the blade till you can see your face in it

Hi Jen,

It depends on whether you have an older or newer model jigsaw. Bosch makes the newer ones with a button you push that will release the blade.
On an older jigsaw, look at the handle from above the jigsaw directly in line with the blade. You should see a screw in the top of the handle. Use a screwdriver and loosen this screw, don't remove it, and when the screw is loose enough, you'll be able to pull the blade out. When you put the new one in, slide it in the slot until it seats.

A rule of thumb is to use the blade with the wider gap and larger teeth on wood, the smaller teeth on metal. Most blades will say bimetal on the metal cutting blades.
Now, the courser the teeth the rougher cut you'll get. So, if you want a nice cut, don't use the blade with the largest teeth. Move down to the next largest.

I don't have a Bosch, so am not sure which codes are for which blades, but you can't go wrong if you go by the size of the teeth.

You didn't say what material the worktop is made of. If it's wood, the second largest toothed blade should be fine.

If you've never used a jigsaw before, I could suggest a couple tips that would help you get a nice job done.
First, put a piece of painters tape or masking tape over where you will cut, draw your line and go easy. The tape will keep the blade from giving you a roughed up top edge.
When you get near the end of the cut, hold a piece of scrap wood flat against the back edge to prevent tearout.
Also, let the saw do the work, don't push it.

Hope this helps, If it does, I'd appreciate a 4 thumbs up, Thanks,

Handie Andie, "woodworker by night"

Use the supplied hex to loosen(not completely) two bolts accessible through the vertical slots in the plastic front plate. Push the new blade into the loosened holding plate with the smooth back edge of the blade against the back wheel. Tighten and check blade firmness before using! Wear protection, use the correct blade, run at max speed before contact, and use a supported cutting bench. Think, plan, execute, and be safe. The motor is only half the power of regular models, so take short rests, and use only for minor jobs.

On the top of the Makita 4304T is a knob, (Top/Front)
This is the blade Installing Lever.

Viewing the jigsaw in the direction you would use it, the Installing Lever is turned towards the Right. Keeping it turned, you then install the jigsaw blade. Once you have the blade up in the Blade Holder, gently release the Installing Lever.

This is a PDF file of the Owners Manual for the Makita 4304T Jigsaw,
(From Makita - Products - Support)

http://www.makita.com/en-us/Assets/images/Products/4304T/owners_manuals/4304T.pdf

[Should the above direct link not work for you, this is Makita - Products -Support, and the download page,

http://www.makita.com/en-us/Modules/Tools/ToolSupport.aspx?ID=248

Left-click on Owners Manual next to the PDF file Icon]

Switch on fan motor not working sw must prove that fan is running! bad motor sw or loose wireing motor sw will by pass start button is released if working!