If all is good with the rear wiring and fittings, I'd check the front sidelights. Try removing the right bulb, then check, and then the left one. Might help isolate the problem. IIRC the wiring to the rear lights is on two circults (I presume so you have at least one side working if there's a failure.
"Y mae dafad ddu ym mhob praidd"
1972 4/4, 1981 MGBGT, 1984 FLHT1340, 1980 XLH1000, 1990 ZX10
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