Cleaning enclosed jacks?

[sfr]

I ordered about 25 Switchcraft switching jacks, the enclosed type.  (Like this)  I got a really amazingly good price on them, as I ordered from an electronics surplus store.   Of course, sometimes you get what you pay for.  The jacks all have a fair amount of corrosion or something on the lugs - solder will not stick to them unless I clean them off.  I've just been running over the lugs with the diamond file on my leatherman and then wiping them on a clean cloth, seems to work fine, and then solder will flow over it properly.

Thing is, I'm looking to start using a large quantity of them in the multi-fx project I bought them for, and this is labor intensive.   I'm lazy.   Also, some of the jacks seem to need a bit of cleaning to get good contact on the tip and NC switch inside.   Can anyone think of something I could just maybe soak these in that would help clean the metal without severely damaging the plastic body of these jacks?

[jonathan perez]

lemon juice

[MikeH]

Try Coca-cola too

[John Lyons]

Is it just the lugs or the inner contacts as well? I would imagine both...
Try Alcohol and see if it's just something that was airborne in the wherehouse. May only be something you can get off with a mild alcohol or solvent. Ten try whatever you have handy. Acetone, laquer thinner etc etc. SOme of these will dissove plastics but you just neet to test on one and see how you do. A Small stiff  brass or steel brush may work fine as well for the outside lugs. Doller stores seem to sell these often in the hardware section.
WD40 works well too. Just get most of it off in the end as it will attract dust.
If you can get it or will use it for other things I would reccomend Caig Deoxit as this is a good thing to use for general cleaning of jacks and plugs as well as any electrical contact. It's made for audio use...

John