Panasonic UF-890/990 - Manual (Page 148)

Troubleshooting
148
If document misfeeding occurs frequently, we suggest you adjust the ADF.
Adjusting the Automatic Document Feeder (ADF)
To adjust the ADF
1
Pull the blue Pressure Adjusting Lever upward
and slide it to the desired position depending
on the condition.
Position Condition
1 To prevent no feed trouble
2 Standard position
3 To prevent multiple feed trouble