Do the resistance checks in the manual first. Note T25 should be 200 ohms, not 2 ohms, if that typo has not bee marked in your manual yet. While doing that, look for electrolytic caps that are bulging at the ends. Also, while you are in there with the ohmeter, check the resistance of the power transformer high-voltage windings. You should have the Hammond power transformer (label on the back side of the core). The black and white wires are the primary and should read about 10 ohms. The high voltage secondary are the orange, brown, and violet wires. You should read about 200 ohms brown to orange, 220 ohms violet to orange, and 420 ohms brown to violet.
That's a start, anyhow.