Check your actual bulb contacts, I have seen a few bulbs where the lead part of the bulb contacts get so flat that they touch the tail light side of the brake light bulb contact and turn it all on. Keep us posted what you find.
There is one about 25 min from me in Reedly, he wants a little more than 6500, but who knows what he would take. I would be happy to go look at it, and ride it for you. Let me know...Kevin