Hi Erik,

If the part you're pulling out is the female part of the friction connector (like a spade lug), you can try gently, make that GENTLY, compressing the connector with a pair of pliers before putting it back (assuming having the pliers in hand won't necessitate any of those additional "hinges"). This is not my recommended first effort though.

Before resorting to such "bigger hammer" approaches, get a can of contact cleaner and spritz the snot out of both parts of the connectors. The problem is likely nothing more than oxide building up on the contacts.

Just in case this isn't already intuitively obvious to you, do not use WD40 to clean electrical contacts. It will leave a film that makes a nice dielectric. But, on the bright side, at least your contact won't likely be intermittant anymore.