Sticky Valve...

You need to remove the valve and clean the cylinder out with a circular wire brush....imo

one of these will do the trick...

...and clean the round metal plunger on the valve stem to get any deposits off...

Thanks... I did that, & Cleaned the piston, to smoth, & put new rubber seals in.

Is better... but she still needs to put her back scruber handle, behind the valve handle for leverage, to open & accross the valve to push with 2 hands!

How about something like this....

for $80.... or if you can swing it, there are touchless controls...it does occur to me that you may have used too much grease or too high of a viscosity, I would try cleaning it at least one more time....

I put that handle on... She still couldn't muve it. Side to side is o.k. / in & out; no.

I would get a round metal brush and hook it to a drill motor and polish the valve housing once more...remember to flush the housing when complete, before reassembly...The valve should not be that hard to pull out, there has to be something binding....

I guess i'l go to Home Depot, & have her pull on a new one... My guess is, she can't... with out 18" of lever advantage. he walking limit is about 35 Steps... 81 years active!

But she can turn on a light switch... That is why I'm looking into a Solonoid Valve!

150 $ ea. Can connect to a wall plug outlet, or 2 switches, hot + cold / 1 switch, just on, whatever...

Is this a Delta single handle? If so, some of the older ones, kitchen faucets at least, have a plastic inner sleeve that screws into the retainer cap (I guess that's what you call it.) This inner sleeve controls the force put on the ball by the outer seal, and consequently the inner seals. I'd use a new ball to make sure it's good and smooth, a little grease on the inner seals and the outer seal, and back off on the sleeve until it just doesn't leak. You'll probably have to do some trial and error. If this sleeve is too far in, the handle force increases quickly. Also wears out the seals quicker.

I think I remember them... has a neopream ball like guide for on & off Up & Down?

The one I'm thinking of looks very similar to this:

The sleeve I referred to is the left half of item 4, below:

The seals are spring-loaded, so they self adjust unless the sleeve is too tight. Then they bottom out and can bind everything up.

My patients with it, has set off a red light & Sireens! I'm looking for a Solonied set up! or "2". Plug in, or switch. (I found one @ $150.00 ea.) once the Temp. is adjusted, it should be the flip of a switch.

Shower controls are so hateful, and just impossible to change without ripping out the wall. Few have access from the back, which is best.

For a senior citizen, who is probably more concerned with function than looks, I would recommend removing the whole valve and plumbing in two quarter-turn metal valves with handles, shutoff valves. These two valves then join at a tee up to the shower head.

Replace the tiles and tidy up as best as possible with cement. Cheap functionality.

I sure was tempted by Ball Valves With Handle extended 8" ea. But, for all that, the effort is still more than a light switch. (Thank You)

Just installing solenoid valves won't control the temp. With both valves on, the water may be too hot or too cold, no adjustment there. You would still need metering valves next to the solenoid valves, and they would need to be reachable from the shower.

Have someone else check the assembly of the valve, fresh eyes may see a tab not in the correct slot, or something in crooked. Like mentioned, you don't want the cap screwed down too tight, either.

Just to be an itch, any electrical switch or device anywhere near the shower must be protected by a GFI device. We surely don't want to zap the old dear.