First use in anger failed! Although I drained and recycled a jugfull before starting the HERMS, the small filter clogged quite quickly. Having cleared it out I could then not restart it due to not having a bleed point installed to remove the air from the closed system to allow the wort to reach the pump. Finished the mash normally and then once the boil was on, I refilled the mash tun with all grain still present and experimented with the rig for a while.
Required modifications have been noted and will be made before the next brew.
Incidentally, it did work of sorts for a while during the mash and the result was a higher SG than expected. Should have been 1048 and came out at 1049. Sorry no pictures
as I became engrossed with trial and modifications.