Today my normally good-running #W 100 engine suddenly began running erratically. It would slow down as if the throttle was being pulled back. I landed and on the ground it ran quite rough at most throttle settings. Actually it started and idled OK, but at higher throttles, it sounded rough. I thought it might be lean, so I richened the high speed needle and flew another flight. No better. next time I leaned the needle 1/2 turn so now I am a little leaner than the original. now the problem seems even a little worse.
The day is nearly over, so I just go on home. I find the ignition module has broken loose from its mount and is bouncing around inside the cowl. I had it screwed directly to the plywood that forms the top surface of the motor mount box. Could this explain the rough running? Do you normally soft mount this component? Mine broke off the mounting flange that is molded into the plastic case containing the electronics.