Kohler is a very poor quality faucet and is usually very hard to get parts forin a timely manner. The more age on the faucet , the harder it is to find the style and parts... their repair parts book is as large as the phone book
You are lucky that they acutally have the parts in stock in the first place..
take the part ouit and try to get another one from that store, it couild be defective .....
if that dont work, call a plumber and ask their opinion,
most likely they will tell you a that your best bet for only $150 is to change the whole thing out and install a DELTA 1700 pressure balanced faucet....
if you are up to the task, and it is feasalbe,
take the 96 buck part back and excahane it for the Delta 1700