Unsticking the thingamabob

[YippeeSkippy]

This one thingamabob on my hot tub keeps getting stuck. It gets to the point where the little cover shield dial (made out of plastic) gets stripped yet won't budge the little turn shaft within.
Does anyone know any tricks to solve this and make the dial usable again? A couple of years ago during a service call the tech told me what to do but for the life of me I can't recall what it was? And at $80/hour for repairs and labor, I guess I can live without knowing. But I do sort of want to fix it all the same....

[attachment=1:2bsgc15j]photo(1).JPG[/attachment:2bsgc15j]

 

[X-PertPool]

It seems like it needs lubrication of some sort. It's most likely plastic so maybe jacks lube but it may be hard to get into there. if you need something to spray into there you can try silicone spray or lithium grease but I'm always hesitant on using those sprays on parts of the pool that come into contact with the water directly. Jacks lube is safe but it comes out of tube so it may be difficult to get it where you need it properly lubricate it.

 

[PJ]

With the hot tub off...un-screw the cap that you have exposed in the second picture (has the square thing sticking out of it). There are some o-rings in there that swell and can cause the valve to stick. Lubricate those with magic lube. Also, if you have a scale problem that can make it stick as well....an acid wash on the innards of the valve would help that if that is the case.

 

[YippeeSkippy]

Thank you both for the responses-
I have very soft water actually, so don't *think* I have a scale problem? How does one do an acid wash?