I have picked a printer for my own office use from freecycle which had the same problem. It was 6 years old and could not pick up paper reliably and printer would report a paper jam. This was the case 90% of the time and I have managed to fix it and only happens 10% of the time.
The rollers that pick up the paper were quite old and grubby and I wiped them down using a microfibre cloth and rubbing alcohol (isopropyl alcohol). This go a lot of the paper dust off the rollers and it could grip the paper better.
Actually from what was said by @adamjpage the other day the only issue is paper jamming in the fuser, the paper pick up issue is only applicable in one tray, it might be worth trying the cleaning, but there are two trays as I understand it @tomnewsom?
My job is making me very tired at the moment. I probably won’t be able to look at
it in the next few days.
There is a five hundred page service manual for the printer. It may be worth a read if you want to have a go at fixing the printer. I’v read the first half of it.
The conveyor belt in the transfer unit that moves that paper past the four toner cartridges seems to get a good grip on the paper. As mentioned on the wiki page, it seems to me that it does not make the 90degree turn inside the fuser unit. I have not figured out exactly how it is mechanically turned, I may have missed the obvious because I’m knackered.
My plan at this point is to read the second half of the manual and run through the sensor tests. After that read the operational overview chapter again and look closely at the mechanical operation of the fuser units.
I’m personally happy for someone else to have a poke at it, but whatever the trustees say.
Please update the wiki page with observations.