Need help with radio button checking/unchecking via jQM/JS

Need help with radio button checking/unchecking via jQM/JS

Let me start off by saying that I am not a developer, I'm a guy trying to finish my website after my code guy went MIA. I'm just starting to learn JS and jQuery so please don't laugh at my codes. :)

So...
Here I need to show or hide button sets based on a combobox selection. No problem there. However, I need the buttons to check or uncheck at the time of show and hide. I wrote the snippet below but it's just not working as expected. Do I need to add "refresh" or something? If so, how? Here is the snippet:

            if (document.getElementById("Combobox1").value=="1.1" 
      || document.getElementById("Combobox1").value=="1.5") {
                      $("#Mat1").show(); $("#Mat1-0").attr("checked");
                      $("#Mat2-0").removeAttr("checked"); $("#Mat2").hide();
                      $("#Mat3-0").removeAttr("checked"); $("#Mat3").hide(); 
                      
         } 

And here is the page (first section, just below the highlight)... http://m.publicmissiles.com/airframes.aspx

Note that it seems ok at first but falls apart after a few combobox re-selections. The buttons are still checked after the hide and that makes a mess.