Try the New Hope site as well. 169.6625 is New Hope's control channel. It is located near your area and has decent coverage.
169.7750 is Warrenton
152.6600 is Weldon Spring
152.6000 is Imperial (may be to far south)
169.6625 is New Hope
Both Weldon Spring and Imperial use frequencies allocated in the VHF paging band. If you have paging transmitters near you, chances are good that you may be experiencing desense of your radios front end from a very popular paging frequency of 152.240 that is in wide use in our area.
If you have any hospitals near your area, it is almost a guarantee that 152.2400 will be in use with a powerful paging signal.
Some of the VHF Moswin sites also use voice channels that fall within the paging bands. If your signal levels are weak for these voice channels, the paging signal could be causing desense just as they do for the control channels.
If you know the VHF sites FCC call sign, try searching the FCC general menu reports. Your search will not return many results because paging band frequencies are not licensed like standard frequencies.
If your search does return results, it will only contain frequencies that do not fall within the paging bands. This can make searching for Moswin sites a challenge as the data is simply not there to search for.
There is another search called CAPRAD that can be used to search for the users of a given "paging market area".
Paging areas of coverage are broken down into what are called "Paging Market Area". You will see areas like BEA69 for example. Using CAPRAD, one can explore the authorized users of those market areas.
Same rules apply when they reallocate federal frequencies and allow Moswin use. An FCC search is almost useless.
It probably is the steel building as one of the sites you tried should offer a very good signal out that way. You may as well be living inside a faraday cage! About all you can do is get an antenna outdoors from the steel building or try and find a window on the side of the building that faces one of the VHF sites you have been trying. That can be hit and miss though but is worth a shot if you really don't want to put up an outdoor antenna.
If you can, program all the VHF sites into the scanner you are trying and then take it outdoors and see if and of the VHF sites come to life.
If reception is being blocked by the steel building, chances are good that you will start picking up signal rather fast after moving the radio and its antenna outdoors.
If this is a portable, the test is easy but if it is a base/mobile scanner, you may need to run an extension cord to power the radio while outdoors.
Also, if 855.6375 works but none of the VHF site frequencies do, try adding the VHF sites control channels to the same favorite list that contains 855.6375. You know that favorite list works so adding VHF frequencies to the 800 MHz frequency will be a valid test to make sure something is not wrong in programming.
You can always avoid 855.6375 if you get one of the VHF control channels to work.
For Moswin, you generally want one of the VHF sites. The STL City site on 855.6375 is just that, the city of St Louis site and won't have decent coverage outside of the city limits nor will it carry as much Troop C traffic as say Imperial or Weldon Spring.
There are some 700 MHz sites popping up across the state on Moswin.
Presumably to fill in coverage gaps.
I've not had the luxury to be within range of any of the new 700 MHz sites yet to see what radios or users are affiliating with them.
At the rate the state seems to be adding 700 MHz sites, it probably won't be long before I can hear a 700 MHz site!
Ok it's been awhile and have not had much luck.
Re-cap
Wanting to hear MoSwin Highway patrol troop C in Forestall Mo.
Radio works fine in St Louis with 855.6375 control channel.
Drive to Forestall and it goes deaf.
Have entered Warrenton 169.775 control and nothing
Have entered Weldon Spring 152.660 Nothing.
I see St. Charles, MO with 700.mhz CC
Should I try those?
Thanks
Tom