Hello N55340, I had problems with my Saito 150. It sound like that "shield" on the bearing might have been the problem. Are you talking about the thin, flat,metal or fiber ring that covers the bearings?? They told me a different story..... but many people doubted when I repeated they told me. They said a new, thick break in grease that Saito was using was causing the problems. (It aslo had a bad carb.... the first problem out of the box). They replaced the carb the FIRST return to IL, then the bearings and the crank on the second trip. My 150 spent more time in the "Brown Truck" then it did in the air!!! Horizon is VERY good about their warrany on the Saito engines. It is just the down time and shipping cost to them that is a hassle.
Since the repair it has been a "Saito as usual"!!! Even with initial problems..... I still love my Saitos. The 3 I have now will start with one back flip of the prop with a chicken stick.

PS.... Another thing I see no excuse for on Saito engines out of the box, is bad settings on the valve clearance. Out of the 4 Saitos I've owned ..... only ONE, I felt, had acceptable settings. One engine had a clearance of .010 on one of the valves !! (.002 to .004 is the required setting). Before running....... I would suggest at least checking the valves..... then reset them after the initial break in, or one hour of running. (the latter being from the Saito manual) .......... lownslo.......