Its easy to tell if the hot fix is working - does the glow lamp come on when the engine is hot,and after it has started the idle will slow down and engine note change as the hot fix drops out.
It is perfectly acceptable to rebuild EDC pumps,if done properly it is as good as new.
BTW,the practice of cooling the pump down is to shrink it - it then performs as a cool pump,this tip has been used for years to diagnose worn Bosch inline pumps on industrial/agricultural engines.

hie guys

does the timed relay work on the BMW 5 Series Diesel, E39 1997 model, i see most instructions are for the range rover, where on the e39 can the relay be fitted, mind you the battery is at the back of the car