inmoov bicep potentiometer adjustment

hello..please hlep ...i followed the bicep tutorial to the point of setting the pot on the elbow...I have the good polarity to ..tried both side anyway....found the 0 on the pot that stops the sevo from turning.with th Arduino.Sketch servo zero, rest, max,90.problem is: that 0 is at 90% of the pot s course ( ex: servo turning clockwise) ,,letting a small 10% for the pot to turn past the 0 and let the servo turn counterclocwise before the pot hit is inner stop...
so problem is ,,,arm can open but can barely close
how can i get the pot to stop at 90 degrees or mid range????do i have to ??? ...or mrl fixes all that ???
I did not connect it to MRL yet ...does mrl adjustment solves this issue ???