Toilets, Sinks, Showers, Tubs and Disposals - Kohler Rite-Temp pressure-balancing valve issues

My 19 y.o. shower valve was messed up so I had new balancing unit and mixer assemblys installed (Kohler parts 500520 and 77759).

Now the shower is either cold, lukewarm or hot. The handle rotates only about 160 degrees, whereas the old one rotated about 270 degrees, but I knew that already. Apparently some internals were redesigned.

The problem is that if I was to use percentages (0% is off, 100% is all the way on) the first 10% is cold, the next 80% is lukewarm. All temperature changes between lukewarm and maximum hot is the last 10% of the handle rotation!

Does anyone know what could be causing that and how I can get it so that the middle 80% of the rotation can be something useful? I'm serious, we have to be very careful trying to adjust the shower when the usable adjustments amount to about 3 degrees of rotation.

I already called the plumber who installed it. His idea of "fixing" it was to send his Mexican helper. Mr "Que?" did not go to plumber's academy I don't think, and apparently his english was not up to understanding what I was trying to convey. He also snapped half the retaining clips off the handle trim cap so now it falls off when we touch the shower handle.

Thanks,
Mark

Did you try adjusting the temperture stop on the mixing cap it is the little plastic ring that slides onto the brass shank with the grooves on it under the handle. I have even seen people remove the stop completely & the handle than rotates 360 degrees. If you look at the picture from this link

http://www.kohlerserviceparts.kohler.com/AccessoriesInformation.aspx?ServicePartID=fed09148f68544989a8d4761e2a0d97b&SearchedString=77759&PageNum=0&PageSize=12

the temp stop is the first ring in front of the large cap. This maybe your problem.