the way to go is a standard spring and new seals all round (including breech seal - an old one can lose you a fair bit of power and is worth changing anyway), new buffer washer, full strip and internal lube. Avoid the square section springs like Ox

. My Mk5 is set up from scratch as standard and is consistantly putting out 8.7 - 8.9 ft/lbs with Bisley LRGs. Flattened it's first squizzer yesterday at about 25 yards, no messing about. Average power for a meteor is about 8 ft/lbs I think.
If by a bucket, you mean a piston, good luck in finding one. Assuming the one you've got isn't completly shafted, look to the piston head seals, etc.
Have fun sorting yours out, I did with mine.
