Some help with central vac

[wingnut60]

Central vac does not seem to have any real pickup power. Bag is empty, lines are clear. Extension cord will contract quickly when hand is placed over end, but still will not pick up much off carpet or floor. Both the main connection and the step pickup work when activated, but still not much work accomplished. Motor sounds same as it did 4 years ago when we got the trailer.
Looking at the power unit, I can't see how it is attached to the framing--it is sitting on an angle bracket that is mounted to the substructure, but cannot see how it is attached to the bracket. Would like to get it out and look it over, but am stymied in finding how to get it out.
Any suggestions would be appreciated.
Thanks,
Joe