OS 46 FX Glow Plug Issue
I had a similar problem with an OS 25 - 1 plug per flight! Making it very expensive to fly... What had happened was that it was going lean in the air, and I had richened up the idlle needle - which at some point fell out completely. So it was sucking air through the hole and leaning out even worse.
If your engine does not appear to be pulling in air anywhere, one possible solution is to put a shim under the cylinder head to lower the compression.
I have not had any problem with my FX's, though.....they are great engines.