The transmission on the Santorin is the same as the Super Maramu, well the big ‘C’ drive.
I presume you have the Perkins Prima M50? They have a Hurth gearbox between the Drive and the engine, and I believe both forward and reverse gears have separate clutches. Have you checked the gearbox oil level? The dipstick must be used NOT screwed in, but with the thread just sitting at the top of the aperture otherwise you can over fill it.
I had to have mine replaced in Marin a couple of years ago. The Amel engine mechanic is very good.
We’ll be in Marin over Christmas and New Year getting our outhaul gearbox separated from the boom plus a few other rigging issues. Then on to Antigua - we’ll look out for you.
Ian and Linda
Ocean Hobo. SN96 currently in Bequia