In the first picture you have a brown wire on bottom LHS. Looking at this, it looks like it MAY be touching the mounting nut on the transformer. If any of the non insulated part is touching this nut then you are running this voltage to earth and it could be what's throwing your values out. If you lose COMMON ( this is not zero volts but a reference voltage that all others are differenced to) then ALL your voltages will be way off.
Slim chance but worth a go..