[wilmo]

In 2008, we used a Gen 2 servo shifter to a garage door spring (200 lbs. force or more to "crack it"). The AM shifters are GREAT at winch applications. Instead of winding up the surgical tubing itself, try winding up 550 cord (google it or ask any armed services member) to winch. It has a 550 lbs. breaking strength in a very small package with minimal stretch. One strand of it could fully tension our garage door spring. Also, check out spear gun elastic tubing as an alternative to surgical tubing. LOTS of elastic strength.