I agree that the mount is a little too small for the 839, but it's the 831 mount that I find awkward to use. I wish they would have just made a BIG version of the 838/839 mount for the 831.
Speaking of which, I think I'll grab my 838 right now and go peek through some sucker holes.
Yeah, I agree with you Ken, I've commented on the 831 mount problems before. If the DEC slow-motion cable was parallel with the OTA instead of perpendicular to it, my major gripe would fade. You just can't balance it in all orientations because of this. Otherwise it's not a bad mount.
It's the same layout that many mounts of the same period share, unfortunately.
I'm not convinced that Swift had anything to do with the 838/839 mount, it is included with other brands of the day so obviously isn't a Swift exclusive. I believe Swift just bought those from someone else and only started from scratch on the 831 mount, according to the accounts I've read.
Lately I've just used my 831 on this all-purpose Edmund mount that I stuck on a very tall, home-made tripod. This works well and is easy to balance. If I ever add a Dec slow-motion, it will probably be a motorized full gear and worm.