Timer switch on GE washer

I have a 3 year old GE 9 cycles/2 wash top loading washer. The timer switch( 175D4232P017 ) has become loose and I must hold the switch in place in the back of the panel so that I may turn the cyle part of the switch to the cycle I want and then pull the knob to start the wash. Checking the back of the panel there seems to be only 1 screw holding the switch in place and nothing else. I tried to pull the knob off the switch so that I could remove and view the switch to see what I must do to repair it, but the knob will not budge. How can I fix this?
Thank you.

You don't state your exact model number, and the number off the timer is not the actual part number (it's some sort of part stamping number). Most likely what has happened is a plastic tab on the timer housing (which normally goes into a slot in the metal, and thus holds the timer at that point) has broken off. The fix is to replace the timer, but instead of buying a new timer, I usually fashion a Z type piece of metal which I can put one screw though into the metal and the other side holding the timer against the metal. Takes a little work, but it's a lot cheaper than a new timer.
If you want to take the timer knob off, you have to pull it out and use a thin tool, like a small screwdriver, to push the plastic clip off the shaft behind the knob, allowing the knob to then come off the shaft. Push the clip back on the knob when off, so that all you have to do to reinstall the knob is push it on and it will lock on the shaft again.