That sounds like an Aqua Magic V hand flush toilet.
There is a water module on backside that can get clogged from debris/scaling. No screen so gunk collects in water module
There is also a flush tube/nozzle assembly that goes from water module to toilet bowl......nozzle can get clogged also.
Is it time for your medication or mine?
2007 DODGE 3500 QC SRW 5.9L CTD In-Bed 'quiet gen'
2007 HitchHiker II 32.5 UKTG 2000W Xantex Inverter
US NAVY------USS Decatur DDG31