Our club had this done for the AD on the L-13 which was issued 15(?) years ago. We found a testing facility by asking around on user groups for aircraft types and EAA chapters. If I recall, we found a guy on the short wing Piper club user forum. Some machine shops have them too and might run the test if you have an A&P there to sign it off. Read the AD carefully and see if there is a requirement for an FAA approved facility to do the test.