Grundig FR 200 adapter static issue

I have gotten the Grundig FR200 hand crank radio (from ebay)  It is about 19 years old and works (with battery charged AM FM bands work perfectly good ---not so at al in shortwave band). No Grundig FR 200 adapter was provided with my purchase  so I looked for one on ebay. I found two adapters on ebay tested both with one a failure(polarity issue) and yet the one I kept (polarity ok) had this occur....On the AM band only static  was heard ( which was so bad the radio was unusable at all--only had heavy static),  but the FM band has no static  and even perfect reception, and lastly the shortwave band is totally dead absolutely no reception at all. MY PROBLEM is how to get RID OF THE STATIC on at least the AM band.  ( I need this band for emergency use) .I tried to fix it by putting on some teflon tape (4 inches wrapped around by the wire part on the adapter that has its pin go into the radio.)  I then  plugged  the opposite ended 2 prong plug into the electric outlet ( NO teflon tape applied here) and turned the radio on and I got no stoppage of ANY static at all on the AM band or anything on shortwave band yet Fm  band was again perfect in reception .I believe this is a wire interference issue that is limited to AM (and perhaps shortwave) receptions. I need to fix the static if I can ...any advice for me?