Recently, the spindle on my Symmons shower/tub control broke. I replaced it myself with a new spindle. Now the water in the shower/tub gets warm but not scalding hot. My hot water faucets throughout the house do get scalding hot. Someone suggested I adjust the screw on the brass fitting that holds the new spindle in place but that didn't work. The shower/tub control lever works fine. Any ideas what could be wrong? Thanks!