Good test to confirm that your HLSJ is NOT doing what it should.
The original MCM FM filter is a good one, but is hard to find now.
http://www.amazon.com/In-Line-Trap-N.../dp/B00EIAFHLK
Radio Shack discontinued their FM trap and Antennas Direct is running low on stock, and will not be replaced. Even HLSJs are getting hard to find. All that will be left is DIY or custom built.
https://www.google.com/?gws_rd=ssl#q...ematic+diagram
The Radio Shack FM filter has poor attenuation at the 88 MHz end to protect TV channel 6, but good attenuation at the 108 MHz end. The AD filter is just the opposite. Neither one would be good for you because you have strong signals at both ends.
Your test results sound like you are on the right track.