Antares 9.80 with Volvo d4 gear issues shaft drive

[Great white]

I’ve a Antares 9.80 with a pair of Volvo penta 225 evc-c 2008. I’m having issues either after a long run or a fast stop and start sprint the port engine will not engage reverse gear. It will rev, the neutral light goes out but no drive, if I rev it hard it will bang into gear suddenly, which isn’t good. Always happens when mooring up. It doesn’t do it all the time. When it does and it bangs into gear it won’t do it again until next trip. The gearbox is a Volvo ms45a (zf45). I’ve had the control block changed the wiring loom changed from gear box to engine connection. I’ve had the gearbox sent to a specialist and no issues found. I’ve also put a manual pressure gauge on the control block and pressure is within manufacturer limits.changed the oil annd filter, Obviously pressure drops when warm. Driving me crazy now. Also swapped over psu units to see if it was that. No different. Also changed throttle head. Any ideas or help would be greatly appreciated

 

[Boaty_Pete]

I'm not familiar with either your engine or gearbox but have been involved with a similar issue on two other boats.
Is it feasable to temporarily attach some wiring to the solenoid connectors for the gear selection and run those wires to a couple of lamps at the helm?
You would definitely know that everything upto the solenoid block was working exactly as expected, leaving only the block or the gearbox with the fault to find.
I definitely recommend not allowing the crunch-into-gear to occur, that's only gonna go one way.
If you've replaced the control block, that (removed one)should be stripped and forensically checked. It may help with diagnosis.