Lower left hand corner of the board is the light triac... (3 legs, screw in the top of it).

Are you using a standard light bulb to test this thing? My guess is with the light plugged in the voltage goes to zero?

There is a small fuse on the lower left corner next to the triac. Be sure that fuse is good. (Power down, pull it and do an ohms check on it).

#--------------------------------
last thing... does your spa have a blower on it? If so, then you need to get a screw into the blower triac on the lower right side - (larger triac - three legs missing the screw). Without a screw tying it to the support post (heat sink) it will overheat.

The fuse checked out OK. I am using a digital electrical tester to do the checks. I checked the leads from the light triac and got 22v on the outside leads and 4.5v on the inside lead and the voltages did not change when I activated the topside light switch. I checked the voltage out of the box at the plug and it is 6v. Is it possible the board is bad?

Well, this is a multi-level light system. It's not going to give you 12v directly. Additionally, checking the other legs of the triac are not going to give you anything that will make sense. The triac is pulse triggered, and to make any definitive determination of function you'd need an oscilloscope.

Press one time, full brightness, second time, medium brightness, third time, low brightness. With a NORMAL bulb - I'm talking about a (4-11 watt) lawn light type of bulb available from home depot etc, NOT an automotive bulb, it should work like that. To test voltage you need to do it under load - (good working light installed).

So, it's 3 presses for light, last press is off. If you're not getting that with a good light bulb - you've either got a defective board, or your topside control isn't working correctly (But assuming it still is according to your initial post that would leave the board as faulty).

I'm assuming everything else works correctly here, if not, then you've got a board/topside proprietary mis-match issue.