I have an older 19" Techwood TV model 19DOMR where the AFT won't lock. I think this is an AOC chassis. It will tune the right channel, just won't lock in. It keeps sweeping up and down about once every second or two. I tried changing out the SAW filter and adjusting the AFT coil, but niether had any effect. Other than that it shows a good picture. I could use any tips on this.