Hmm...I know East Windsor went to some type of LTR Trunk System. I seem to recall south windsor changed to something else as well. I'd recommend visiting
www.wlfd.com for two reasons. That site is the Windsor Locks Fire Department. As I am sure you know, they border. They have a very extensive list of area frequencies, verify you have the correct info.
If you do indeed have the correct info, you likely can't receive it from your location (which wouldn't be a huge surprise for 800 and 400 to not make it to Mansfield if they aren't as high power as EMS). If that is the case, or either way, WLFD offers a live scanner on their website that among other things scans South Wiindsor. If you use winamp, you can even get alpha tags.