#1
Hey people - I think I need to replace some electronics on my guitar, I have a problem and I think it is the pickup.

It is an Epiphone SG g400. If I plug my guitar in after a while without using it, the neck pickup is reeeaally quiet sounding.
It's sorta weird because if I play for a few minutes on the broken pickup, it eventually sorts itself out and starts playing again. But does occasionally cut out again too.

No problems on the bridge pickup.

I don't really wanna spend money getting it checked at the guitar store, so if anybody could help me diagnose the problem here, that would be awesome.
#2
Sounds like a bad wiring connection. Pull off the cavity cover and start pokin around the wiring for the neck pickup.
#3
Try spraying contact cleaner (I used DeOxit) on the pickup selector switch and then engaging the switch several times. I had a similar issue (pickup not working, partial volume, scratchy as all hell) on an old Epiphone SG and it fixed it right up.
Guitars:
Jackson Kelly KE3 - MIJ (Distortion/Jazz)
Jackson DKMGT Dinky (EMG 81/85)
ESP E-II Eclipse Custom (JB/'59)
ESP LTD EC-1001FR (EMG 81/60)
Fender MIM Strat

Amps:
Mesa/Boogie Dual Rectifier Roadster 212
Laney IronHeart IRT-Studio
Peavey Vypyr 30
Peavey ReValver Amp Sims
TOOOO many T.C. Electronic Pedals. . .
#5
I had a problem like this on my Flying V. Couldn't find anything wrong, took it to the shop and it turned out to be a dirty pot.