The 3-way switch is certainly a good suspect, worth getting some switch cleaner and squirting it in there to see if helps. But without using a multimeter to check continuity, you'll never know for sure as the cleaner may make no difference.
The 3-way switch is certainly a good suspect, worth getting some switch cleaner and squirting it in there to see if helps. But without using a multimeter to check continuity, you'll never know for sure as the cleaner may make no difference.