DF-704 (C368) Reads 8 1/2 x 14 original as A4

[SAR]

This is a weird one for me. When a legal sized original is placed on the DF feed table, the size is read as A4 instead of 8 1/2 x 14.
Copier has latest firmware and function version. I have done the ADF width adjustment twice and checked the 2 length sensors in service mode sensor check.
I even tried unplugging the sensors on a working feeder at the shop to see if I could duplicate the problem, but no luck.
The customer has been able to get it to work by placing a small rubber disc about 1/2" thick on the front edge of the feed table which raises the paper up slightly
and then it reads as 8 1/2 x 14. This had me thinking the feed table might be warped, but no matter how I twist it or torque it by hand, it still reads the size wrong.
I will probably just swap out the feeder and fix it in the shop, but wanted to see if anyone else has run across this issue.
I will definitely post up the fix if I don't hear from anyone first.

[Woxner]

No need to swap. Ck the varister on the edge guides. The can go bad. Also do the width adjustment for the feeder if you replace the sensor

[tmmdmmm]

No need to swap. Ck the varister on the edge guides. The can go bad. Also do the width adjustment for the feeder if you replace the sensor

Second this. Try the min/max adjustment. Believe min is B6 and max is A3 for all Bizhub DFs
Edit: And the 704 should have B6 and A3 listed on the sticker for a quick adjustment, although you should measure 125mm and 297mm for accuracy.

[SAR]

The cause of the problem was a bad Document Length Sensor/1 (PS-8 part #A5C1M50100).
Part 4 in the picture. Luckily all of the sensors in that DF-704 feed table are the same part on the DF-701, so I was able to steal the part from an old DF-701 feeder.
Df sensor (2).jpg

[aberock]

System > ADF > Width Adjustment > min/max adjustment