[Hallicrafters] BFO on SX-16

[Mike & Kathy Ball]

I just replaced the 'BFO Injector' pot on my SX-16, in hopes of repairing the BFO.  When I turn the BFO switch on and crank up the pot, I do not hear the oscillator, and the pot glows and smokes.  I thought perhaps the pot was bad, so with the help of George Frost (who sent me a replacement), today I installed the replacement.  This time, when I carefully turned-on the BFO, and brought up the pot, again-no tone, and in addition, I heard a crackle from the pot at about the 3/4 full position.  I quickly turned the control off, in hopes of not damaging the pot that George sent me.  Would anybody be able to give me a clue where I should look to trace the problem.  I did change the BFO tube (6J7), no difference.  Just wondering if anybody else has seen a similar problem and could share the experience with a not-so-experienced SWL'r.

Thank you much, and thank you again George.
Mike