Today I refitted the part after, I plastic-welded and JB-welded with fibre-glass mat the casing and put everything back in greased with special silicone grease and resealed the lid on. Fired up and exactly the same.

The drive belt is rotating the big cog but when I apply resistance (to simulate brake applied) to the output drive the wobble-plate 50:1 reducer slips and makes the noise I was hearing. Everything was sound as a pound and smooth in the house so it must just be too much wear in everything, especially the offset shaft of the swashplate and it can't transfer the load anymore, thankfull ECP have put the price back down so ordered a new caliper

Thanks guys.