GE agitate and spinning problems

I am having some problems with my GE washer, and hope you guys can help me to buy the right part. The first thing that happened was on the timer when you push it in so you can change the cycle that you want, some how the knob broke and it just spins so you have to grab the inter part of the knob so you can change cycles.( You can still turn the washer off and on with the outer knob). Then it quit spinning every now and then, now it wont even agitate. Thanks.