Don't buy a new actuator. It will cost you nothing but time and a bunch of WD40.
Pull one of the door panels and pull the actuator. Clean it up with Qtips and WD40 inside and out. Work the switches back and forth and clean it some more. When you think it is clean, put it back in and try it out. If it works, be sure to lubricate it before you put the door panel back on.
And, yes, mine quit locking before it quit unlocking. If you can hear the switches trying to work, then the power is actually getting there. Also, there are only two wires going to the actuator. I think that if your doors unlock, the lock function is just a reversing of polarity.