If your scores were better last month, and the holes were cleaner than they are now, then a seal failure could account for the lower score and the torn holes in the target.
The BSA Scorpion ( like the Original pistols and rifles) came from a time when some dodgy plastic was used to make the seal and it could be that it has finally perished and a replacement could help solve at least one of the problems
The new replacement seal is likely to be made from a newer type of plastic that should last longer that the original factory fitted one - but if your Scorpion does still have its original seal still fitted then it has already done very well.
I had a .177 Scorpion when they first came out and it was very accurate (but also very heavy).
It is good to still see them being used in the 6 yard MPL postal competition so I hope you get yours fixed soon and your accuracy returns
Rossendale Target Shooting Club. Every Tuesday and Thursday evening 7 - 10pm.