It would be nice to find a schematic for this specific variant , but only
one Google Ref for the number on the end face label
JCM2-20-06

I'm wondering if there is any significance in the bodged 1/3 W R
replacements
R70 of 5K6
R7 of 5K6
R48 of 100K

unfortunately none of these numbers agree with any JCM2000/ DSL schemas that
I have.
Similarly I cannot find the 2K2 HT line dropper for (a) half of V1 mentioned
on these schema