27" JVC tv model:AV-2648S no channels 02-28

27" JVC stereo tv model:AV-2648S,year:May 1989,chassis: none found on back but on board: SX-1198A.One day no station reception for channels:
2-28 above 28 work fine,I checked soldering in tuner and fine. Anyone have any common repair tips for this old unit? as I could not find any repair tips anywheres,it uses the old rectangular style tuner #:

AK7092EP-A05 TEMH3-073A PD03B73A

Thanks in advance for help/replies.

Tons of free service manual downloads:

then click on "click here to see the files" followed by "video" followed by "products".

Sidney Dartmouth,Nova Scotia Canada