hi all, my weihrauch (i think the model) hw95 (its a bit dated but does the job) is starting to make a twangy sort of noise when fired, is there anything i should do like greasing the spring or something, or is it time to buy a new one. p.s it still seems to have the same firepower but 1 shot and the rabbits are off, where usually they'd just prick theyre ears.