I am working on a Genie GS-2646 lift, can not locate SN plate or stamping, that is a 24v system (4 - 6volt batteries). I have a question on the 24v dc motor controller. I am getting 24.8v at B+, new 2 ga ground to B-. When I activate lift up, terminal 1 shows 24.7V and terminal 3 is giving 5.6V, which all checks out according to the genie motor troubleshooting guide. Intermittently the motor will work, but more often than not, I show 24.8V on M-. Is there any cause for M- to show voltage, aside from a bad motor controller? I want to make there are no other possible conditions that would cause controller to show voltage on M- before ordering a new controller. Any advice would be appreciated, and if needed I can attach the schematic I have since I can't provide SN.