This pool/spa was (as near as I can tell - no records on this foreclosure) built in the mid 80's
It has two Intermatic classic electro-mechanical timers; one feeds both the filtration pump and the second timer, which controls the booster.
As near as I can tell, these are dead - when I arrived only one set of trip arrows was present - I splurged and got new ones for the missing side (on or off, don't remember which)
2Q's: can you see any missing parts? Are the red and green plastic clips appropriate to this model?
Would a new Intermatic of the same design (guessing this is a 100-series) be plug-compatible? Mainly, I'm concerned about fitting into the obviously specifically-designed cabinet. It obviously says: Put Intermatic timer here.
Have they changed the dimensions and/or mounting provisions in the last 30 years (yes, I do feel ancient - why do you ask?
To answer the obvious: no, I don't know how these work aside for how to set them. Looking behind the wheel, it looks like there is a (now reduced to knob) device which the on/off tabs were to engage. I'm thinking they are worn past the ppoint they will engage the on/off arrows.
New Q: is that part field-replaceable for less than te cost of a new timer?
Another new Q: are there digital timers also plug-compatible (220v on both)?
Thanks again for your patience