I agree that Americans pay far more for health care than they should. I agree that Bush's medicare giveaway to industrial pharma was grossly irresponsible and that it has contributed a massive amount to the crater that currently is US fiscal policy. And I do not honestly know how people who consider themselves conservatives could support either that or the tax cuts, especially when the United States was on course to actually pay off its national debt.
Returning to the issue of social security, the statistic Fisher cites comes from Table IV.B6 of the trustees’ report, which is extremely conservative in its assumptions (assuming essentially zero productivity growth over the next 50 years) and thus - even at the worst - would require only a minor tax addition to permanently solve without reducing benefits.
I do not much like your suggestion that since the Republicans instituted tax cuts the surplus is gone and there's nothing we can do about it, but will add only that if Gore's proposal had been adopted (Republicans at the time were championing the terrible idea of dumping social security funds into the stock market while cutting top-end taxes), even the "infinite horizon" figure would be nowhere near where it currently is and it would likely be possible to reduce the payroll tax or increase benefits. And given all this, I don't know how to reconcile your claim that this is not a Republican problem with the fact you claim to be a rational fiscal conservative.