Whether to rebuild or replace depends...
Your boat may be a 1980 model, but that doesn't mean the toilet's that old. In fact, it's doubtful that any of the equipment on it is still original. I don't THINK Wilcox toilets have ever been OEM equipment on Hunters (on a 1980 boat, I suspect the original toilet was a either a Mansfield 751 or 752 or possibly a Par) which means a previous owner installed it...but when? If it's only a couple of years old, I'd rebuild it. Older than that, depending upon what model Wilcox it is, I'd replace it. I suspect the model is prob'ly the inexpensive Head Mate, but Wilcox also makes higher end models that are built to last 100 years. Replacing one of those with a Par or other inexpensive toilet would be tantamount to replacing a Rolls Royce with a Yugo because a tune-up for the Rolls costs as much as the Yugo. If replacement is the best option, I wouldn't recommend replacing just pump assembly...because pump assy's aren't stock items at WM or any of the discounters, but special order, you'll pay just about as much as you will for a comple new toilet off the shelf. The only question will be whether to go cheap again...or pay a bit more for a much better toilet.But I'm not altogether certain that it's holding tank that's backing up into the head...unless it's full to overflowing and the vent is clogged, it's not likely. unless something else is messed up in the system. You can certainly find out easily enough, just by replacing the joker valve in the head discharge, which is a $10 item. And yes, I would definitely replace the "bag" holding tank!Btw...my own boat is also a 1980 vintage...In the 3.5 years I've owned her, I've replaced just about everything on her. It's definitely been an education in boat systems and, in many cases, how not to install them. When I bought her, the wiring looked like someone had started out to knit a sweater, then changed his mind and tried to turn it into a pair of socks...and things went downhill from there! So you're in for lots of fun, but it will be worth it.
