funny whine in first gear

[jiversteve]

Lots of parts are available from Rimmer Brothers as the box was originally a Triumph unit.
Problem areas are the gear clusters and input shaft as they are Marina specific. There are also some poorly documented variants, ask Jubileenut
If you want to keep your car on the road, its probably best to find a 2nd hand box and have that rebuilt. Then spend a weekend swapping gearboxes boxes and clutch.