[TenTec] Omni-C 40m/80m alignment question

[Marinos Markomanolakis M.D.]

In my newly acquired 546 Rx sensitivity increases towards the higher end and seems to go down towards 7.0 Mhz.
Also in the 80m band, sensitivity seems to be much more towards 3,5Mhz, gradually falling towards 4Mhz

Going through alignment of the front end and VFO mixers per the manual did not help to any significant degree.
Suspecting that coil L1 (the one not supposed to be touched during front end alignment) may be somewhat off for the preselector to track, but I am hesitant to disturb it, especially since there are no instructions for its alignment in the manual.

Any ideas or help would be greatly appreciated.

Thanks, 73
Marinos sv9dru / ki4gin