[R-390] Mechanical filter tests?

[DJED1 at aol.com]

Well, I finished recapping and aligning my Amelco, and all looks well with  
one exception.  I found that I have about 10 dB more loss through the 16  KHz 
filter than the others.  Never noticed it before, because I never use  that 
filter.  So I'm debating whether to try and replace the filter or not-  it's a 
tight place to work, and I'm not sure what I've got as a spare.
I've got one of the ATC IF chassis with filters, but I need some guidance  on 
how to test the filter and what the results should be.  I did a quick  setup, 
feeding the filter with a URM-25 and measuring the output with a high  
impedance AC meter.  It measures about 13 dB of insertion loss- is that  about 
right? 
Thanks for any advice
Ed  WB2LHI