I installed a New Tub and shower about 7 years ago, For some reason I get very low water from the tub and Shower, It is a 2 handle Hot and Cold, with a Nob u pull and it goes to the shower, you have to jump around to get wet. I know very little about Plumbing, the water pressure at the Sink in the Bathroom is great. Do you think its time to replace the Mixer vaules, with a Whole new unit? I think its Perless I know its a Brand name. Any help would be Great.