[removing recoil spring from m1 20g]

Any suggestions for removing the locking nut to allow access to the recoil spring for cleaning.

It appears to be locked and the nut is somewhat beat up from previous attempts to access.

Trying to get the gun to cycle low recoil loads consistently.

Roy

[Benelli S90 M1 20g no longer cycles weak loads]

4 yo gun has worked fine with 7/8 oz skeet loads now will not cyle second shell from magazine to chamber.

Should I replace magazine spring 064c or recoil spring 054b?

Any suggestions appreciated. Where to order etc.

Thank you

Royc