[Boatanchors] 30L-1 low power output problem on 80m band

[Yongsurk Lee, HL1FB]

I put a wattmeter between TS-520 & 30L-1 to test.
All bands except 80m show 100W input & 600W output.
20W input and 100W output measured on 80m band.
When 30L-1 is off, 100W output measured from TS-520 on 80m.

I tried adjusting the input coil L18 but almost no change observed.
Any idea?
de HL1FB/WW6N