Drew's schematic does NOT show the 200k resistors on the IBAM board. All it shows is where they are connected in the circuit. And the value of that resistor depends on the value of the complementary coupling capacitor.
Back when Drew first published the schematic for the modification, the prevailing consensus was to change the stock .047uf capacitor to 0.1uf. Of necessity then, and in order to maintain the "constant," the combination of 200k and 0.1uf was established. A lot of water has passed under the bridge since Drew first published (2/20/2010) and some refinement has gone into the the issue of changing the coupling capacitors. Suffice it to say that 1) if you're going to install an adjustment modification, the original combination can remain. 2) If you are intent on changing the capacitor, then the most readily available capacitor is .068uf with the complementary 220k resistor. Of course, as originally advocated by many, Jim McShane being one, the use of a .1uf cap will maintain the "timing constant" as close to the original design as possible when used with a 200k grid resistor. That being said, I sincerely doubt anyone has ears sensitive enough to pick up the differences that would undoubtedly be shown on test equipment. Just sayin.'
Now none of this is directly related to the OP's original issue, i.e. a "hot" 7591 and, perhaps, a faulty IBAM construction. As Larry and gadget have already pointed out, the grid resistors need to be in circuit, whatever the chosen value of the complementary pair.
