Hp 4250 jamming when switching paper size

[COPYDOCAZ]

This machine has 2 paper drawers I know the base machine is working fine I ran 200 copies in the shop, when I took it back the machine jammed when it switches from letter to legal intermittently. I tried another tray 3 assy and got the same result. the machine also has a duplex unit which seems to work great. The machine is reading the correct paper size on both trays. Very confusing.

[copyman]

You didn't say if you can run 200 sheets from tray 3 without jamming. Is it only happening when switching trays?

Look at the pad on the paper feed solenoid. Mostly every one I see now sticks because foam rubber has turned to glue.

Also most likely nothing to do with your problem but check the exit actuator that has a pad that stick.

I removed the sticky residue with alcohol or WD-40 then put black tape where pad was. You cannot leave bare because sol may magnetize and stick closed.