If you have a volt meter, you can pull the plugs for the motors and then test voltage at the pins of the 4-in-1. I can't tell you what it should be, but:

(a) I do remember someone (maybe mrasmm) posting the correct voltages around here a while back. Do a search.

(b) If you post the voltage readings you got, I am sure mrasmm will be around soon and he can tell you if they are correct.

If you don't have a multi-meter, you really need to get one. If none of the above is an option, then I think that you would have to buy a new one and see if it works better. [&o]