Bizhub 363 DF 621 jams 2 sided originals

[tsbservice]

Hi Guys,
I have dealing with J66-01, this is for ADF turnover section.
This occurs only on 2-sided copy/scan job. It always jams every single original like:
-original exits completely, without trying to reverse
-original jams on switchback when two rubber rollers(exit rollers) try to reverse it back
-original manage to reverse once but failed on the second pass(this is rare case)
New set of pick/feed/sep rollers are installed, all transport rollers(plastic and rubber are cleaned).
I read about updated parts which fight problems with originals feeding, maybe scan motor adjustment.
I had worked many years with Toshibas, now that KM staff is new for me(don't have access to more than SM, Parts list), so treat me gentle like a newbee
I plan to take this DF with me to test it on another machine and eventually swap parts.
Any thoughts and ideas would be greatly appreciated.

TIA

[fixthecopier]

I would be looking at the actuator/photocell for the turnover section. change the photocell after checking fo a sticking actuator, then maybe swap boards.

[fixthecopier]

This is the board I mentioned,, A143 PP7Y 00 PW Board Assy

This is the only photocell used in that doc feeder. A143 PP48 00 Photointerrupter

[tsbservice]

That one was real lemon. Whe swapped all parts that are supposed to do with these from working DF-621, and still no luck. I have to replace whole DF with another one as clients urged to scan big piles of docs.
Anyway, thanks for suggestions fixthecopier.