Right..
Took the 97 apart.
Nothing obviously wrong. Spring may have had a slight cast but couldn't be sure it was that slight.
Removed all lube and re applied .
Had a spare spring in the cupboard exactly the same length so put it in.
4 shots to zero then 3 pellets through the same hole. Chrono says 11.47.
Back to where it should be!
Bloody springers I am off to buy a S400