Laserjet Pro 400 color 451nw tray 3 jam but no tray 3 is available

[csoup50]

I believe I have figured this issue out. This printer has two sensors on the bottom one where tray two slides in and there is a second where tray 3 would feed in if there was a tray there.

If you turn the printer upside down and slide tray two out, you will see tray 2 has a piece on the front that intersects a sensor. The second sensor is the black paper opening at the bottom, its a slit that has a lever that you can move with folded paper. In my situation the tray 3 sensor has failed. All I did to solve this issue was flip tray 2 sensor for tray 3's sensor. It works! Its not too tough to flip these sensors around. Tray 3 has 4 black screws around the metal pate and a few silver screws, remove them and then you can get access to where the sensor is. The sensor on tray 2 just slides out, of a metal holder. Flip them and reconnect everything and you should be printing again.

It would of course be better if we could just replace these sensors so if you know what it takes let me know, otherwise this solves this problem. 

[csoup50]

Looks like this is the sensor. I have one coming to try it, I can reply if it works.

SNR-M451-ENT Sensor