It's been my experience that worn valves cause problems similar to a missing waterkey cork... the horn goes flat and the notes don't center as they should.Imperial wrote: What is most affected by worn out valves?
Should you have your piston plated?.... well... that depends on how much value you put on your horn and the condition of the casings. In severe cases, the casings are worn to the point where they are not round and can be tapered from top to bottom. Sometimes it's not just a matter of plating the pistons back to size. They may have to be plated oversize and the casings have to be trued. A repairman familiar on how to measure the casings should be able to give you an answer. Most shops don't do their own plating and honing and the pistons and/or the whole valveset needs to be sent off.
If your pistons and casings are worn badly, I would be leery of any shop who says they 'can do it all'. I've found that it's usually better to remove the valveset and send it off. It's a top-action horn, the valveset will probably have to be taken off, anyway.
