Hi all,
after applying 0.09 thick tape, the problem is significantly reduced and almost fixed, but alas, still ever so slightly off at infinity.
I have ordered some industrial grate .1 thick tape since I suspect the 0.09 one was 'roughly' 0.09.
Will update once I receive and applied the tape.
Out of interest which tape did you use? I have an RX with a focus problem the other way, infinity gets hit before it makes it to the hard stop and I suspect someone has had the mirror off before.