Saving Old Seagulls

Hello,
i have Seagull Century Plus-fixed drive (identified on SOS)
A few days ago i was driving and exhaust just dropped down for 3-4 cm (1-1,5 inch ) i tryed to get it back but cant ( rowed back home)
took it out on land and somehow got it back up and tightened that metal ring on top, and yesterday gone for test drive and again dropped after 8-10 mins
metal ring on pic below:

Now is there any other thing to squeeze or bolt up something or just that metal ring ?
and i have driven that motor for 10 years (not all the time , its my backup motor, but i use it here and there) and never got that problem, so pls help

Thank you


ps.
im from Croatia and sorry for my bad english

I would drop the gearbox, remove the exhaust and clamp, clean everything up, remove all the oil and re install.
Hard to see, but looks like an ally exhaust, so have a look for any cracks around the top.

Mine did that once but i wasnt going to row home, i just presed on despite the noise. Hasnt done it since just tightened the clamp. If it keeps doing it id just put a small SS self taping screw at the bottom of the EX tube.

U aint seen nothin yet. My english wasnt that good at school 50Yrs ago, also failed in Latin.

Thank you for reply's.
I'll try with SS self tapping screw today

your motor appears to be running the wrong prop ? Possibly get better performance running a five blade hydrofan ah but now I see which side the carb comes out , sorry my mistake .

Hey, don't worry about your English I find it hard to understand my granddaughters, they've got their own language. Have you seen how they talk in the text mesages to each other????????

As for your small problem, I have three 40+ engines and they all have a small self tapping screw at the top of the exhaust. Could be the answer.

Gerard