This is a symmons-temptrol. Leaking only at the tub spout. I don't know the model number but it is able to divert to either shower or tub. The tub spout leaks. What internal part should be replaced. I have a schematic listing parts T1 all the way to T55-c.
The parts are further grouped in several sections. For example, T4 is actually a grouping of T1, T2, and T3. However, none of the parts is actually given a name.
Any advice would certainly be appreciated. Thanks in advance!