My Vibralap is an oldie. It still is running well, however as the rubber balls have been replaced a couple of times. The motor has no appreciable load, so it should last forever.
The aluminum plates can handle 120/240 grit through 600 or pre polish but not coarser grit and polish should have its own pan with a felt base. I have had great success using three grinds, 120/220., 600 and then something like Rapid Polish 61. Each stage takes about 6 hours, although sometimes on the first grind I do it more than that or repeat the process if the kerf lines are deep.
I used to surround each rock with a rubber boot so they would not chip each other and leave fragments in the grit. I now use the method at left to save a great deal of effort!
When I bought my used Vibralap from a fellow who had used it to death, he said that he always used it outside because it splashed so much. It is cold in the winter and I had no interest in running this thing outside so solved the problem with this hack at left.