Yaesu 800DXA

Question

I have a Yaesu G-800DXA rotator that still works but it has suddenly started to act up when I press the button for it to go right it does and then suddenly it will go back to the left while I am still holding the button down also it does this going the other way as well I have checked all the wires etc and all are good it doesn't do it every time just every now and then can someone tell me what is going on Thanks