I have an old Epiphone Riviera on which the controls and switch crackle when used. As there is no way to access the electonics via the back, I was wondering if anyone knows the best way of cleaning up the connections etc.

throw a piece of soap in a big bucket, throw the guitar in it and throw it all in the dishwasher. Either that or you could go to your guitar shop and ask the shop keeper to clean it for you.
tie string round the pot shaft then take the nut off the pot, pull it out of the F hole, do what needs to be done, then pull it back into its hole with the string
Get off this damn forum and play your damn guitar.
Thanks for the advice. As I'm a complete novice I'll probably get an experienced techie to do the job!
to clean the pots? get electrical contact cleaning spray and spray the pots...

to change electronics, etc, the string method is the best way. Its really hard on some guitars so goodluck.

American Strat
Epiphone Valve JR head - Volume Mod'ed
Custom 1x12 with Private Jack speaker
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Boss DS-2 Distortion
Boss MT-2 MetalZone

Gretsch Acoustic