Where the o/p of the transformer is connected between the plates/heatsinks, there are four "press in" diodes of which one or more might be blown, more likely than the transformer.
If they need to be replaced they can be pressed out in a vice with a short tube and a drift of some sort.

Ok...That makes sense too!....The trouble will be finding replacements if they are toasted!...

I just want to check everything before I power it up as I dont want to toast my switchboard either...