Best Way To Clean Faders (80s Mixing Desk)

I have come to acquire an old DAX 16 channel mixing desk, but the faders are quite dirty and feel like I'm pushing through sand :P this is also problematic because whenever the faders are moved on a channel with a signal going through it, the sound gets grainy due to the dirt buildup blocking the faders signal. what's the best method of cleaning this? thanks in advance for any help you can give

Spray them out really good with compressed air, then hit them with some Deoxit D5.
If they are as bad as you say though, your best bet is to just replace them.