HP4050 'ker-thumps' during printing

[total1]

HP4050
Trays 1 and 2

Issue is that the sound coming from the HP4050 goes 'ker-thump" [this is a serious IT defined word, you realize! :-) ] when I send a page to be printed. Sometimes recently, the during complete feeding through the path the letter sized page gets jammed, but not always. I can print with this noise going on. The 'only' thing that I've done recently is to replace the Tray 1 traction feeds and put it back together. The noise appears to be coming more from within the HP4050 rather than anything close to the Tray 1 feed mechanism. Feeding from Tray 1 (manual) or Tray 2 seems fine but the noise is apparent whether or not the letter comes from Tray 1 or Tray 2. I've attempted to use the full pass-through of the HP4050 so that the output comes out the back rather than the paper doing a '180' and wrapping around.
Ideas of the issue and how to fix?
TIA!!!

[MichaelTech]

Uh,,,,have you had any service on this unit?
What is page count? The noise is probably the fuser, but may be just the toner is bad. You should replace the feed assy., found behind the MP assy.
The registration, and the fuser also if over 100k pgs.
Possibly the tray2 feed/pick-up assy. is going bad.

[ooojaya]

try taking the little black wheel next to the feed roller in the tray out. you can leave it out without any real problems. sometimes they hang up and make a noise. it just slides right off the axle and is easy to do and check. if that fixes it, you should get a new torque limiter (the part you just took off) but as I said, you should be able to print without it.