Actually, on a Europa with a traditional Switchcraft barrel jack, the jack may be fatigued beyond repair. You may have noticed that we have migrated to a different side-mounted jack (like
this one on Monty), since the barrel jacks tend to have a limited 5-10 year lifespan.
You can order a prewired replacement from us for $15 or get 2 for $25 so you'll have your next spare on hand. Sorry, but there is no method to change tot he new long-frame jack if you currently have a barrel jack.
Note that some premium cables tend to wear the jacks more than standard cables. Seems that some gold plated connectors are overplated on standard ones, and therefor have a larger diameter than .25 inches. Go figure! If you can feel a scraping physical resistance as you insert your cable, then it surely needs replacing.
One other possibility again with the premium cables is that some have connectors that are longer and may slightly overshoot the contacts on the very standard jacks in the instrument. If you have no trouble with the contact just before the cable is fully inserted, you might want to put a nylon washer over the cable connector first to compensate.