Transmission Identification Problems

[MarkDiver]

Hi, I have this transmission on my boat, it works in reverse, but when in forward it doesn't engage. If I wait it eventually does engage but not at full power. I'm assuming that it needs replacing and then I can get it refurbished. Its attached to a Perama M20 engine. There are no ID plates or labels on it anywhere.
My first question therefore does anyone know what type of transmission it is please?
My second question is there a comparable gearbox I can buy that I can swap it out with such as a Technodrive or PRM.

Many thanks for the help. - btw excuse the mess of oil and muck, its in the process of being cleaned out following an incident.

[FPNC]

Start with a photo of the transmission. It may be possible to ID it.

Interchanging a Hurth/ZF , PRM or TMC gear is normally a straight forward process. They do not 'drop in' but it is always possible.

[MarkDiver]

I thought I had uploaded a picture - hopefully this works now. Thanks.

[FPNC]

Looks like a Hurth HBW 100 or ZF 10M. Ratio can be determined using a photo tach on the crank and propeller shaft.

It can be replaced with a like unit or a PRM 90 or TMC 40. The current adapter plate and drive plate can be used. I highly recommend replacing the drive plate.

[MarkDiver]

Thank you FPNC, I appreciate the help and advice. Cheers.