My dough holder jumps out of the base and will not lock in. This makes the machine unusable unless you hold the inside down.

Check that the safety lock pin is releasing from the base. It is the thing in the tube down the side of the bowl that the lug on the lid engages with. It stops the motor running with the lid off..

https://www.google.com/search?q=Kitchen+Aid+food+processor+bowl+stuck

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Make sure that the bowl is fully tightened in the bowl lock. If this does not solve the problem it may be that the lock disc itself needs to be replaced or that the amount of dough is more than the dough hook can handle.

Seems like a broken bearing or wheel inside the machine

You need to make sure that the hinge pin is tight, turn machine completely upside down and tighten the slotted screw up inside the pedestal. If that doesn't fix it you will need to check that the locking lever is properly engaging in the slot. You may need to "SLIGHTLY" file the slot in the pedestal that the lever engages into. If you go mad with the file you could wreck the slot.

You will need to disassemble the entire front panel to get access to 2 other screws inside. Remove the top panel first, then the control panel and then remove the front panel.

Not fully understanding this but it sounds like you are opening the lid too much and spoiling the rise. Only open the lid when at the dough stage if necessary.
Bread will not keep warm, it will steam and go wet and soft in the pan. Open the lid when the cycle has finished and remove the loaf.
Try re-setting your machine by holding down the start button till the display goes out.

Turn the unit off and disconnect from the electrical
outlet.
2. Remove the tank from the housing.
3. Unlock the housing from the base by turning the lock
knob to the unlocked position.
4. Lift the housing straight up and place to the side.
5. Unlock the wick holder from the base by turning the lock
knob to the unlocked position.
6. Remove the wicks from the wick holder.
7. Follow the weekly cleaning instructions.
8. Insert new filters into the wick holder and lock the wick
holder back onto the base.
9. Replace the housing onto the base and lock it into place.
10. Fill the tank and place back into housing.
11. Repeat Operating Instructions.
It will take about 30 minutes for the humidifier to reach

MAKE SURE IT IS CLEAN UNDER THERE AND THAT THE HOLDER WHEELS ROTATE FREELY

I'm not completely familiar with the model, but even a floating bobbin holder as you described should have some sort of a hold down. There may see a small swinging arm on the bottom right side of the bobbin area that needs to be located over the bobbin case to hold it in place. Let me know if this doesn't work.

I have the answer to the TR2500BC pan popping off the base!! My husband and I made a loaf for testing the jump off. Ah HAH! I set the pan in, ok. felt it was down all the way. When it started to knead the ball and stop to reverse...it popped off. We looked at the side hook on top. ok. It popped off again. It was when my husband made sure the two tabs on the under side of the pan was in the opposit direction of the two buds in the base. at that point you MUST set the pan down with force until you get that distinctive click, click. Rock the pan front to back a bit as you push down. It has worked every time since I started that process. I make two loafs of bread a week with no problem of it hopping off. ENJOY.