It's leaking where the 1.5" waste hose connects to the toilet.
Iow, where the discharge fitting connects to the pump housing? I suspected as much. It's one of three things...and the following applies to ALL manual toilets:
1. The flange on the joker valve is the gasket that creates the seal between the discharge fitting and the pump housing. OVERtightening the screws will pucker that gasket, causing the connection to leak. So unless doing that has permanently puckered the joker valve, backing out the screws a quarter turn should stop the leak. If it doesn't try soaking the joker valve in boiling water for a few minutes to see if it fixes the pucker. If it doesn't, it'll cost you new joker valve.
When you attach the discharge fitting, just tighten the screws enough to start to feel a little tight...flush the toilet. If it doesn't leak, they're tight enough. If it does, tighten NO MORE THAN another quarter turn. Flush again...and keep tightening NO MORE THAN a quarter turn till the leak stops.
2. You used a straight fitting where a 90 is needed, causing the hose to pull to one side, lifting the fitting on the other side.
Replace the fitting with a 90 to relieve the stress.
3.. You overtightened the screws enough to crack the pump housing. Easy to do on a Jabsco toilet, but possible on any toilet if you crank 'em down hard enough.
Only cure is a new toilet pump. :cry4
NEVER use ANY pipe dope, or any other sealant in a sanitation system! And while a heat gun should be used only by someone who's highly skilled with one, a blow dryer is safe (unless you're brain dead!) and a lot easier to use than boiling water.