Hi,
At first I´d analyze the error behaviour:
set the stopper to 50mm (without cut)
then
* set the stopper to the position (p)
* do a measuremetn with a ruler (r) from stopper to cutting edge
* cut a sheet and measure it´s length (s)
pos p | ruler r | sheet s
(forward from 50 to )100mm | ? r | ? s
fwd 200mm | ? r | ? s
fwd 300mm | ? r | ? s
fwd 400mm (no cut)
back 300mm | ? r | ? s
back 200mm | ? r | ? s
back 100mm | ? r | ? s
give us the six values of r and six values of s
With these values we are able to detect whether there is an accuracy problem, a general precision problem and/or a hysteresis problem.
Don´t hurt yourself.
Klaus