Here are some additional notes:
The focus and cutoff controls share a common supply. If the cutoff adjustment has no effect, that supply voltage is the problem. If the cutoff adjustment works, and given that you have verified that the focus control has no effect, the problem is either a bad 1M resistor (the previously-mentioned R26), or a poor connection between the focus control wiper and the CRT focus electrode. Verify that there's continuity between the wiper and J2-9. Since the appearance of your problem coincided with a repair job, it is possible that the focus pin in J2 got dislodged or damaged. Inspect it carefully to verify that both mating surfaces are where they should be, and that they're clean.
There is also a 100k, 1/2-W resistor (R6), and a 0.01uF/1kV capacitor in the focus circuitry on the CRT board. If the resistor is open, or if the capacitor is a short, you will also have focus problems.
The focus and cutoff controls share a common supply. If the cutoff adjustment has no effect, that supply voltage is the problem. If the cutoff adjustment works, and given that you have verified that the focus control has no effect, the problem is either a bad 1M resistor (the previously-mentioned R26), or a poor connection between the focus control wiper and the CRT focus electrode. Verify that there's continuity between the wiper and J2-9. Since the appearance of your problem coincided with a repair job, it is possible that the focus pin in J2 got dislodged or damaged. Inspect it carefully to verify that both mating surfaces are where they should be, and that they're clean.
There is also a 100k, 1/2-W resistor (R6), and a 0.01uF/1kV capacitor in the focus circuitry on the CRT board. If the resistor is open, or if the capacitor is a short, you will also have focus problems.