Sorry my bad.
Sorry my bad.
Look I really don't think you've got a gearbox issue mate. Sounds more like an intermittent spark dropping out. Can be quite "violent" and yes, can even seem as if the g'box is jumping in/out of gear.
I think you need someone to cast their eye over it and drop it in a test tank or go for a run with you and check spark etc...
I had the guy come over who serviced to check it over,he found the bush in prop was flogged out.
Prop is a solas stainless 4 blade,in which he told me cause of 4 blades makes engine vibrate worse.
Also dropped all oil out of gear box & was clean.If I had gear box problems there would have been shiny bits in oil.
Going to send prop up to get fixed.
Thanks
Forgot to add boat would idle fine,go in gear then try to get on plane it vibrated.
lol,till my little fella got that scared he shouted are we going to die.