Laserjet 4100DTN Tray 2 problem with legal size paper.

[Galane]

I have a LaserJet 4100DTN and some legal size paper it will not feed from either tray 2 or tray 3. I've replaced both feed rollers for both trays, the clutch for tray 2 (it was groaning, doesn't now), and the separation pad and roller for tray 1. Tray 1 will feed this paper.
Feeding from tray 2 or 3 it always says paper jam but it doesn't move the paper one bit, like it's not even trying.
Letter sized paper works fine, better now with the new rollers.
Can paper be too thin for this printer?
It has a J6057A JetDirect installed.

 

[Koen]

Check the switches on the paper size sensor board.

 

[Galane]

The problem was the two semi-circular paper 'kickers' that push the top sheet into the feed rollers. If the paper was thin they'd slip. I installed new ones of those and new feed rollers, even though the old ones on one tray still look and feel good. On Tray 2 they were shiny. I also replaced the rollers in the manual feed tray 1. No more paper feed/jam fails.