[5ash (Philip)]

I have an 8" Newtonian and want to bring the primary mirror about 1-2 cm forward in the tube , will need to buy some replacement springs. What criteria should I use in selecting them. Since the mirror is ultimately held in position by push pull screws the strength of the springs is not so important , however what about the diameter? Also what do I ideally replace the existing adjustment and locking screws with?
Regards philip

PS the secondary is oversize so it's not an issue