Grinding noise from shower with no cartridge

[EWek11]

when the single delta knob shower gets hot a grinding noise starts and the pressure drops significantly. If you turn the handle to cold, the noise stops and the pressure returns, but the water is cold. As it gets back to being hot, the process starts over again. I've opened the hardware and think the problem has something to do with this little plastic ball (see pics).
Picasa Web Albums - EKing

Thanks in advance for any help/advice you could give!!

 

[havasu]

Purchase a repair kit at your local big box hardware store and reinstall everything in the kit. I'm sure your problems will disappear. If I remember correctly, that model has two options available. One is steel, and the other is nylon. The steel one will last you longer for a few bucks more.

 

[EWek11]

Thanks for the help! Am I looking for a faucet repair kit? Do I need to know a model # of what I have or anything? Are the steel and nylon referring to the "ball" that is inside?
thanks again for the help. Much obliged!!

 

[havasu]

Just brink your ball with you and look for the Delta repair kits. Match the size of the ball and stem to the new one, and you are good to go. The kit contains a new ball, a few springs, rubber caps, and a couple of "O" rings.