Trouble with mod Servos under Servotimer 2 lib

I have three servos I am trying to control (two modified for continuous rotation and one unmodified) with the Servotimer2 lib. I have read several places that it is a bad idea to control the servos with just PWM and that it is better for the board and servo to use the lib. The servos have a 1500u sec neutral and are clockwise to 1900u sec.

However when I use servoname.write(); the following happens...

any negative value and spin any value between 1 and 50...increasing velocity spin in clockwise direction any value over 50...max velocity in clockwise direction.

Is this just a modification error (specifically the pot in the wrong place?) which would be the most difficult to test and potentially damage the servo? Or am I having a misunderstanding with code?