Latest check. TP now 3.2 mm .Spring space 206 mm. Spring 256 mm plus 5 mm guide flange giving PL 55 mm at rate 32 lb.f/inch.
Forces acting. Uncocked 69 lb.f cocked force 170 lb.f
ME Hobby 8 fpe, SD 8 fpe, Exact 8.6 fpe, Bisley 7.5
Found a few Express 7.9gn giving 9 fpe.

Think we're there or thereabouts now. Cocking effort about 2/3 of original and feels good in hand.
More spring/pre load fiddles tomorrow hopefully.
Thanks again for input/looking.
P.S. Tempted to try FWB 124 spring for info.
What's the informed view on result of refitting original weight and/or spring? Massive "slam" and that which may not be discussed?