Recently, I have been unable to get a substantial supply of hot water to the main bath tub. Water pressure for the hot is very low, and substandard for cold as well. The bathroom sink is hooked into the same line as the tub; pressure is great there and I have no trouble with water temp on that faucet. Water pressure to the rest of the house (kitchen sink, dishwasher, master bath, washer, etc) is good.

I have checked all shut off valves, and they are all open. I believe this problem to be beyond my repair skills, but I would like to know if there is anything else I can try before calling in the professionals.

Thank you