Hey codeman, have you tried to use a mounting bracket and screw it down or even some industrial Velcro along the entire bottom of the radio and the bottom of the cubby you have it in. Pretty sure some good Velcro would hold fine. But the mount would definitely hold it being screwed down. Either top or bottom, either will work, for the bracket that is. As long as it works for now and the radio isn't getting hot, then use it!! Have you pulled the towel out after s qso and see if its hot or not?? May want to do that just in case. If all there is is hot air to blow, the fans can't do their job correctly and will just be circulating hot air. Just some food for thought. Have fun with the radio, they are a very nice one. I wish my magnum 257HP was built a bit better. But it does have good audio on both AM and SSB. Anyhow. Be safe and have a good one.
73 and God Bless