Well, the plot thickens and this is getting very interesting.
I put the original spring set back and reset the suspension.
Quite a different bounce and if anything far easier to get a nice firm pistonic motion.
If anything, the irregularities in the shape of the older springs allows more fine adjustment.
The resonant frequency is also higher on the older springs, with the bounce rate faster and also a bit firmer.
<Serge if you should be looking in, cover your eyes now!>
Had another listen tonight and I actually think it sounds excellent with the old springs, and the gap between it it and the P9 is clearer. It now sounds characteristically bouncy, with what I'd call the 'Linn gallop' - a sort of propulsion to bass and fast percussion. Yet it places all of this in a warm and cuddly sonic blanket, almost like someone has applied very mild reverb.
The arm and more specifically the bearings are clearly doing their job and are in fine order. On hot tracks you can hear the sub-chassis roaring away as the 774 acts as a conduit for energy leaving the cartridge. Did I mention reverb.....
I've posted some sound quality demonstrations over at our place. I think they are well worth a listen. If nothing else they demonstrate that the evolution off the LP12 hasn't been entirely positive
if you really like what the original did best.