Tail Lights Sporatic Function.
Since I bought my 86 Elan, I have experienced intermittent tail light faults that illuminate the idiot light on the panel. Since I got back from the body shop, I decided to replace all of the tail/brake lamps at once, since I had previously done the same in the front while the car was in the shop. I found all of the filaments intact however, the contacts on all the lamps were severely pitted! Looked similar to arc burning. Went to Walmart and low and behold, they stocked the 1156 and 1157 Sylvania lamps. Cheap fix.
I guess it was to be expected after 31 years. I think I'll do the same on all of my instrument lights that also experience random issues with going dark.