So sometimes it's best to call in a professional and save yourself the aggravation, which is what I did. All 4 TV's now work correctly without static. Here's what was done, and I hope it helps someone else down the road...
1) Checked all barrel connectors at all cable ends (there's a lot!). All were compression fittings rather than crimped fittings, but some had the braided wire strands wrapped around the copper center wire which causes a signal short, and some were loose (not installed correctly). Replaced all questionable connectors
2) Bedroom coax is longest run from splitter, and had a second splitter in line. I assume that this further split the signal to provide connection to the "loft". I will never need a TV in the loft (heck, I'll never BE in the loft!). Removed this second splitter, and taped extra coax to the other one so it didn't get lost in the wall.
BTW - split signals reduce the strength, putting more emphasis on quality connectors and connections.
3) Bedroom TV still had static, so replaced 4-way splitter with a 4-way signal amplifier. This corrected the problem and all 4 TV's work great! Unfortunately, the amplifier required a larger hole in cabinet to reinstall into wall. This was then covered by placing a "blank" wall plate adjacent to the existing wall plate. In a dark closed cabinet it is not noticeable.
In addition, an HDMI cable was run from my Dish receiver directly to the main TV, and also left the coax connection for air antenna connected. All TV's now work without static as they should have!
I appreciate all I have learned on this forum, and hope my recent experience may help others. Thanks!