The flow from hot water side is too slow, cold is fine. I think I raise pressure by loosening up the hot water spigot. The handle up by the tub is "frozen (or rusted) in place". Is there a way to raise the pressure down in the basement at the water tank?
It is a stand alone claw-foot antique tub, repair is expensive

Does you have separate handles for hot and cold. I would guess yes and that makes me think your valve stem is getting plugged with crud, likely from a water haeter that isn't being flushed periodically. Shut off you water main and open a faucet somewhere in the house. Unscrew the packing bonnet nut under the knob and back the stem out completely. Clean it of debris and Change the washer while you are at it. Stick your pinky into the hole and rub the seat to make sure there are no burrs or irregularities. Before reinstalling the stem you should hold a towel over the opening of the stem and have someone turn the main on for a moment to flush the line. Reinstall and you're good to go.