Ricoh D131 Service Manual page 1486

This means you must lower the front end of stopper 2.
Then, compare the L3 measurements.
In this example, imagine that L3 is longer at the front than at the rear.
Look at the table, in the row for FM1, and the column for L3.
'F Long' means Front measurement longer than Rear
'F Short' means Rear measurement longer than Front
L3 is longer at the front, so we have an 'F Long' situation again.
Then look at the next line, below 'F Long'. It says 'Raise F on S3'.
This means you must raise the front end of stopper 3.
Stopper Adjustment Procedures
1. Use the "Skew Correction Reference Diagrams" and "Skew Correction Reference
Table" in the previous section to determine the location of the skew and which stopper
needs adjustment.
2. Now you are ready to do the adjustment on the multi-folder unit.
3. The illustration above shows the location for each stopper adjustment.
Each stopper is equipped with two screws.
The black plastic screw is the Set screw and the metal silver screw is the
Adjustment screw.
SM 93
Skew Adjustment
D454/D615