HP M451dn jam in tray 1

[Copeya]

was brought in for jamming and saying jam in tray1.
Checked all sensors and blew out, came back to ready and got to change the tray 2 feed rollers and now it switches from tray 1 jam and please insert tray 2
When does feed it only goes about a 1/2 inch up and then shows jam in tray 1 that wont clear without a hard reboot.
Any Ideas

[tech28]

Very common problem, just had another one doing the same thing(yesterday), have seen so many of them doing the same thing, jams from tray one, firmware, clutches, solenoid,switch's does not solve problem. HP 2023's, 2025's, 451's, 475's, 476's, that whole family/series, all same feed assemblies, only thing did not try was the board on top of the laser unit, that fires the solenoid. Cheaper to just switch machines out, or just part them out. If you do find a solution, please post it. Good Luck. Have seen many ideas shouted out here and in other forums, but... nothing working to solve problem.