The reason the traces around the relay burn up is because the flipper end of stroke is not adjusted right and both Bally / Stern made those traces too small on many SDB versions. Apparently those traces are weaker than the 5a fuse before the bridge. Misadjusted EOS, someone does lots of flipper holding, and those traces vaporize.
The traces going to the collector of the power transistor burn up because the coil locked on and the playfield fuse is the wrong value.
Bally / Stern also made a mistake by not fusing the DC side of the cabinet and head coils. If the knocker in the head or the chime box in the cabinet has a coil lock on, there is no DC side fuse like what is under the PF near the flippers. Coil locks, fuse does not blow, trace vaporizes.
I fused the chime box and knocker in my Mata Hari and is good idea to do to all Bally / Stern games.