taillight blowing fuses

i have a 1984 kz550. I've had it a few months with no electrical issues to speak of besides a main fuse blowing once. recently my instrument lights went out, the warning lights still work but the spedo/tach are not lit. a couple days later i was told my tail light is out but the brake light still works. after replacing and blowing the tail fuse a few times and running through the wiring i am at a loss. are these at all related (i don't see anything telling me they are) and why could this be happening? the bulbs are good and there hasn't been any damage associated with this new problem.
any help would be extremely appreciated as i get off work late and would like to not be hit from behind on the freeway.

Here's the color codes of the tail light/brake light(two seperate circuits):

BRAKE/TAIL LIGHT Can be an # 1157 dual filament bulb
RED, Running or Tail Light.
BLUE,(sometimes with a Red stripe) Brake Light Circuit.
BLACK with YELLOW stripe, the ground circuit.

I suspect a wire may have rubbed through the insulation, causing the fuse to blow. If possible, disconnect the tail/brake light at the bullet connectors and see if the problem is at the assembly (the brake light/tail light),or further up the wire harness.