If all that's needed is head replacement and cleanup, it's no big job. You can do it yourself. Measure the shell's diameter (take three measurements, at angles to each other -- old shells can be out-of-round), then go to Elderly Instruments or Stewart-MacDonald and order a plastic head of that size. Get a "high crown" head unless the stretcher band (the metal hoop that pulls the head down) is not very wide (1/2" or less). Shipping will be a few days, and then just remove the old head, clean the surface and pop on the new. It's dull work, tightening the brackets, but not difficult.
If the existing head is a skin head, you can get a skin head, but those replacements are trickier -- you have to soak the head in water, put it on wet, trim off the excess, and get it just right when it has dried. Not that easy, not that hard, but not worth it if you're looking for a good tenor banjo sound anyway.
As Bill Day said, you can call or email me, but HMT or do-it-yourself is how I'd do it, myself.