It helps if you can visually inspect the jack closely. The contacts are generally nickel plated steel and if the plating is worn off any cleaning type fix will likely be short lived and replacing the jack (they're pretty cheap as aviation parts go) is the only "cure". But if the plating is intact I doubt that alcohol will help much, something slightly acidic (like the previously mentioned orange juice) will do a better job of removing the oxidation. With most jacks you can also bend the contacts to apply more force to the engagement which will help keep the oxidation off (inserting the plug wipes it clear) as well as help maintain good contact if the plug moves.
It's also quite possible that the actual problem is the plug itself. If the plug's surfaces are dull and/or tarnished you might solve the problem just by cleaning that up. Again something slightly acidic or mildly abrasive (a red rubber eraser works pretty well as does Scotchbrite) should restore the shiny more conductive surface needed.
BTW, "Tuner Cleaner" can do a good job with dirty jack contact surfaces but that does require some mechanical abrasion to work well (repeated insertion of the plug might work). And I wouldn't worry about the cleaner's residue attracting "dirt" as dirt is generally not a problem (inserting the plug will wipe any "dirt" off the surfaces) the real issue is oxidation and the cleaner residue will actually help ward that off.
