Fuel gauge sender unit refurb

[E T]

I recently bought another 750f jap spec tank, I took the sender unit out so I can sort out slight rust in tank. The problem is previous owner had put something in tank and shook it to try and remove rust but all it's done is fuck the sender unit, has any one had any luck repairing unit or now of something similar that I can fit. I know it's a long shot but any info wellcome.

cheers