Product review (4 stars): Symmons TA-9 Temptrol Valve Washer Repair Kit
If there is just a small drip coming from the tub spout when your Symmons Temptrol valve is closed, you can sometimes repair it by replacing the washers included in this kit instead of buying a whole new spindle and seats. At least as long as the hot and cold seats are in still good condition and the piston inside the stem of the spindle moves freely.  I don't often get that lucky, but happened to this time around. I find that removing the old cold washer retainer ring is easier using a small mini-hacksaw to score it in a couple of different places and then snapping it off by flexing it back and forth with a pair of pliers, rather than attempting to unthread it. The old hot washer pops out easily using a utility knife after removing the existing retaining screw. The replacement hot washer also included a new stainless steel retaining screw as well. The ring gasket for the threaded spindle cap just slips in place after removing the old one. Considering how little it costs, this washer kit may be worth giving a shot first, as it doesn't require any special tools to install and could possibly save quite a bit of expense on additional repair parts.