I would get a different type of machine. Try the standard: Large Belt
or Drum sander w/ fine sandpaper belt. Most pros use those types of
machines for a reason--they're so much quicker and easier.
If you can get a good quality orbital type, then that'll do for
finishing, but it is slower. Sounds like you might be using a machine
designed for polishing (?), which sounds unlikely to me to function
effectively as a sander.