My toto toilet has a problem with the Gmax fill valve. It fills, pauses, fills again a little, pauses and so on until finally stops. I cannot find instructions anywhere as to how to adjust this valve. Do you have any information on this valve?

Without any introduction here are the pictures of the Tub to be converted: [ATTACH]2775[/ATTACH] [ATTACH]2776[/ATTACH] [ATTACH]2777[/ATTACH] [ATTACH]2778[/ATTACH] [ATTACH]2779[/ATTACH] This is our spare bathroom. We are planning a major renovation to our main bath and need another shower in our home. It seems like a straightforward job, I've helped some people out with tiling but never done anything on my own. My real concern is the current tile, or actually whats underneath the current tile. A little backstory; I bought this house almost two months ago. It was a foreclosure that was fixed up by Fannie Mae but sat for at least a year. This bathroom was completely redone. From the looks of certain areas of the home that were fixed, I'm not too confident anything in this bathroom was done the 'right' way. That being said, I don't really know where to start. Obviously the drywall needs to come down, membrane goes up, backer-board, thin-set, tile, grout. I would really like to leave the tile that is already up since it is relatively new and decent looking. I plan on using the exact same style and size of tile for cost reasons. Since this is a regular tub and not a shower, is it possible there isn't backer-board behind the current tile? If there is backer-board behind the current tile, is there anyway to be sure(without ripping it all out)? And IF there is how difficult will it be to replace the drywall with the cement board, without having any level issues? Final note; I had a plumber at the house fixing some items and asked him what it would take/cost to install the piping to add a shower. He quoted me at $250, saying that was " a lot cheaper than if I went through the company" since he would be doing it on his own time. First off, is that a good price? Secondly if I'm ripping out all of the drywall around the tub, couldn't he install it from there? He was telling me he would have to cut out drywall from behind the valve( which is in our spare bedroom). Any valuable information is GREATLY appreciated! Thanks everyone :thumbup: