Are they plastic or metal?

Personnally, I don't like doing things twice. If you have the budget, take the plunge and replace them all... should be able to just replace the "guts". No need to replace the outer bodies unless they are damaged. 14 years is a good run. What brand are they.

The valves are Toro, black pastic outside. I can get model numbers tomorrow morn.

Thanks,

I have found that plastic valves are so cheap that it does not pay to rebuild them. If they had been metal, that would be a different story and I would rebuild them.

I would replace them all. The cost would be outweighed by not having to do it later at a time that is sure not to be convenient.