When you bought fr3 there should be a crome long tool with hex on one end an drill bit on other end and is flex able in center ( 12inch long). When slide wouldn't move you get drill and this tool and place tool in back of slide motor. On end of slide motor rubber plug remove ,insert tool an drill motor , run drill will retract or push out slide ,must be a reversible drill.
PS ITS A REAL PAIN TO GET AT MOTOR its on top of slide on inside center must remove wood covering. check on line there are videos. good luck.