OK, it was working - do we know how long it had been working before it died? Weeks, days, hours?

I assume that is a voltage regulator that has been cooked there? I wouldn't be too hasty in connecting up a replacement PSU or transformer until the reason the problem occurred in the first place is addressed. You might just end up cooking the replacement as well. A good look through the schematics would be in order to find out what lives at the other end of that particular supply rail - for example, I wouldn't be surprised if the shaker motor has some sort of problem - but it could be anything really. Check that the fuses are correct, too - if they aren't this might give you some clues.

I guess a faulty transformer could cause the problem on the power supply board, but I am suspicious that the problem lies on the other side of the PSU? That is, whatever caused the voltage regulator to cook may have caused damage to the transformer at the same time.

Someone with more experience will be able to give you more insight.