Just pulled the cowl off of the Edge 540 that I picked up from a swap meet Saturday and something I haven't seen before. It has a TOC-53 and bolted on the carb is what looks like a plexiglass plate. This is on the top side where the metal cover has a small pinhole in it.I've never seen the clear plastic cover on one before. Is this to prevent the pressure from forcrd air into the hole? Just wondering if this is something homemade that someone put on the carb May be a foolish question, but I had never seen this on a carb before. Thanks