Hi Jen,
I suggest ask the shop to apply dielectric grease directly to the gold contacts on connector . As in the image above you would apply the grease directly to the 4 gold spades stiking out from connector. In my view the issue is related to contacts rubbing more than dust/dirt getting...
I had same problem @2300k. 100% agree with what Dave above says this is a connector issue caused by fretting(vibrating and rubbing in electrical contacts which leads increased resistance) or dirt and dust ingress . Any contact grease(dielectric grease) will prevent it in future. After cleaning...