Outer Limits 4x4 Board

my fuel guage in my LWB wagon has been being a bit choosey as to when it reads accurately, rather then signalling well below empty. I realise there is a bit on the float arm in the top of the tank that has a series of contacts. The contacts dont look to worn and when i had a meter at the guage plug it seemed to work fine. Only thing i can think is that it may be moving sideways a little from time to time and missing a contact?

also when i took the guage sender unit out i noticed a white 'cooler block' looking thing in there... it is too big to come out the hole - any ideas wat it is??

i have just realised that the little fuel lift pump i have has not been running for some time... no power to it...when i connected temp supply it started with the ticktictittatitkcit noise that i havent heard in months... does this mean the injector pump has been sucking the diesel right from the tank??

any ideas where this pump might be supplied from to save me some wire searchin??