I know this post is old, but wanted to put this info out there in case someone searched for this info like I did. The shop vac on my FB550 went out. I was not successful at finding a cheaper version of the 240 volt shop vac that I could get in the US. Still, I was too cheap to buy one from HP for an enormous price. I decided to find a replacment motor instead. I found one on Amazon that was very close in size and matched the specs of the motor in the shop vac. It is used in a central vac system which is why it is 240 volt. The one I bought off Amazon was 1/2" taller, so it left a 1/2" gap when I put the top and bottom side of the vac back together, but it did not affect the performance of the vacuum. The cost of the vac motor is $142 and it took me about 30 minutes to replace it. Here is that part number if anyone needs it.
Ametek Lamb 5.7 Inch 240 Volt 2 Stage Ball Bearing Motor 116110-01