Hi Tom,
Been there, done that and in the end, had to go back to the original commode
and make do. Most contemporary commodes do not have the configuration that
the older ones had. Sometimes, you can get a fit, other times you can't.
If the condition of the commode its self is OK, there are a few things to
look for. One is the seal at the gate valve in the commode. The second is
the valve right at the entry to the commode. And lastly, the reservoir at
the top of the commode that refills the bowl after the water is shut off.
The reservoir has a rubber float valve that closes when the water hits it
and allows the reservoir to fill. When the water is shut off, the valve
opens and drains into the bowl. Frequently the valve deteriorates and
doesn't seal - thus water spraying inside the commode housing as long as the
water is on. The water flows down over everything and it's most impossible
to tell where it is coming from. The valve is most easily damaged by
overtightening and splitting the plastic or allowing a freeze to do it's
damage. The commode gate valve seal might be the most problematic as many
Thetford models no longer stock parts.
I just by-passed the reservoir to eliminate the leak as I couldn't get a
valve for the reservoir. Replaced the commode valve and now have a
serviceable commode, but looks it's age. In my case, a replacement is not
made that would fit my '74 Argosy.
It's not a big deal to take the commode apart, just don't try to force any
plastic parts. Study it and take your time.
Regards,