Andrew R Stewart 

The #1 problem I see is the lack or securing the brake reaction arm. This allows the arm and the connected internal parts to rotate on the axle and cause bearing slop and loss of braking. #2 is not having the cones and lock nuts counter tightened enough to prevent the axle from rotating during securing the axle nuts. Again slop or overly preloaded bearings result. Note that both issues involve the wheel's removal and reinstall by someone who isn't experienced. I have to say around here we nearly never see a lack of lube due to heat. We do see really gummed up old grease sometimes. There was a local bike shop, years ago and long gone, that would do quickie CB overhauls by just loosening up the insides and pouring in a tablespoon or two of kerosene. Much like spraying WD40 into a STI shifter pod this would soften up the gummy grease, at least for a while... Andy