Screw not screwing

I've just changed the FEP sheet for my Saturn 4 ultra and when I tried to rescrew the vat back into place the right hand screw will not tighten unless I angle it slightly, however it does screw when the vat is off. I took apart the machine and checked the connector and it seems fine, I've attached a picture of the connector.

I also tried to remove the connector while I had the machine open however one of the bolts does allow for purchase with the Allen key :/