Firstly does VR stand for Visual Replica, LM3875 amp with 1 valve, a bit
smaller and lighter than the original.
Originally thinking channel change sw prob as dirty ch good, clean
cutting out (with owner). All PbF looks good under magnifying ispection
lamp, any known stock fault?. It looks like return to engraving tool
with nylon tip rattling pcb while listening to output on phones
technique to zero in + redo usual suspect solderings