I was a Makita fan before I bought this sander. I could not keep the sander in a straight line when sanding, also had a lot of vibration and noise. Read on a blog about this problem. Took the base plate off and sure enough it was warped and even broken at the top around the bearing. Purchased a new base plate. Installed it a very simple job. Now the sander works very well. No more problems.
I am sorry to say that the paper holder systems are designed quite a bit bit differently. And you cannot interchange the system from one to the other. The best thing to do is just replace the parts you need to repair the clamp system on your BO4550.
I have a Makita BO4556 palm sander with a broken catch for one of the sand paper clamps, and I have ordered the replacement base (the plastic piece).
How difficult is it to replace that part? It originally looked as though you just unscrewed the four screws on the bottom to take it off, but that doesn't seem to be the case. That just removed the rubber pad piece with its metal plate.
Does the whole unit have to be disassembled to get to the bottom plate? Are there any instructions available?
If I remember right i think you only have to remove 912117-6 Countersunk Head Screw and then the plastic holser pulls of the shaft along with the bearing(which should also be replaced while you have it apart).Hope that helps.Good luck.Tinker