My problem is that I can grasp concepts and ideas, but when it comes to solving specific problems with actual numbers, I seem to shut down. Specifically, it takes me much more time (read "hours") to solve problems that ought to take 10 minutes. This is a particularly bad thing on tests and exams.

I believe that the difficulty I am having stems from so little exposure to symbolic reasoning in the past 5-6 years. I am looking for resources, techniques and advice to "turbocharge" (to use CFAR terminology) my ability to absorb and deeply comprehend technical material, so that solving problems becomes second nature.

So, typically when you look at a math problem there's a process you can go through that reliably gets from the problem to the solution. Do you have a good idea what all of the steps in this algorithm are? Can you identify where you're getting stuck?

My guess is that learning how to do that will be the largest speed boost.

I suspect that watching people solve problems, interleaved with solving them yourself, is the best way to practice. It might be possible to identify the step you're bad at, and set up problems which only go through that step- but this may require cooperation from someone else to be effective.