Help! Leaky Grohe Model 34-436

[ShrinerMagic]

My shower is equipped with the Grohmix Integrated Thermostate Valve 34-436. It started leaking awhile back, about a drop/second. Called the plumber and replaced the wax cartridge (part #47.111) for a total cost of parts and labor of around $500. Shower still leaked after he left. Called him back and he advised that I would need an entire new faucet to fix the leak. That was about 6 months ago and we have lived with the leak all along.
Fortunately, decided to look at the web and found this site. Saw a similar thread back in 2006 and it looks like what I need to replace are the stop valves, probably both the hot and cold (part #08.355) based on what I learned from the 2006 thread.
Although I'm handy, I've never really tackled a plumbing job before other than replacing a kitchen faucet and a few leaker sink washers. Can those stop valves be replaced by a simple do it yourselfer? Do you need any special tools? I read that the o rings need to be greased. I don't even know what kind of grease one uses to do that. What kind do you use?
Does anyone have an idea what it would cost to replace the valves? Is it possible just to replace the o rings as opposed to replacing the valves?
Any help would be most appreciated. Thanks so much.
Moe

[jimbo]

Well, that looks way too complicated....which is why this is not a plumber's favorite brand. http://www.grohecatalog.com/product/34436/

But as with many shower controls which have dual function...meaning water control and temp control....it looks like he replaced the wrong part. The funtion of the wax cartridge is to pass water through, with the hot and cold balanced to desired temp. But bottom line, if water is offered to the wax cartridge, it is going through. That part is NOT responsible for water on/off, or in your case....water drip. Yes, the two stop valves, index #9, would be the problem. One for hot, one for cold.

I see a stop valve washer kit. I don't have any experience with this one to say whether it is worth the time to try an overhaul the stop. or just replace it.

O-rings can be greased lightly with waterproof faucet grease, available at any hardware store, or with silicone faucet grease, also from hardware and plumbing stores.

[ShrinerMagic]

Thanks for the quick response. Is this something that I can do, not being a plumber? Would taking apart the faucet and getting to the stop valves be intuitive? Would I need special tools?
Moe