I just got back from a few weeks away. During my trip I experienced a weird noise from my gearbox. At about 1700rpm it it made a sound like a highspeed football rattle, which disappeared when the revs were backed off.
Increasing the revs again allows trouble free cruising for anything up to an hour. It must have happened about 20 or 30 times from Kate Boats to Wigram's Turn, but the last leg from Braunston to Banbury it only happened once just coming out of Braunston. So it is intermittent and very irregular, but nonetheless disturbing to hear.
The Gearbox has done about 16,000 hours since installed. Never so much as hiccupped with the exception of a clutch change about 5 years ago when, on putting it in neutral, the prop shaft continued to turn very slowly.
Now I have actually taken the Box out of the boat to get it serviced and am having trouble finding someone that services 150s close to Banbury, but upon reading some comments here and other places I am not so sure it needs such a costly service. I would like to hear anyone's comments on this situation. Should I go for the service or just do an 'oil change' which seems to be the favourite recourse.