I may as well. At least my SG-613 is still good. Where is the damper diode and what is the sub?

As I recall--The Efficiency-Diode, a metal-cased thing- (In the KV1810) was fitted to a small tag-strip under the heatsink and a large blue film high voltage rated tuning-cap was also attached to it...
--I think the cap was rated at 1,500V as I recall....
Both the Tuning cap--And the diode should be replaced. Its incredible how HOT the blue film cap gets in these sets, and important the cap is a very good quality part, or an original type part....

Failure of either will lead to SG-613, SG-6533 (or whatever its got in there) will suffer....

The damper hangs off the SG-613, usually on a terminal board, along with two caps - typcially a 330pf and a .014uf to .018uf Blue Epoxy Dipped cap. The blue cap tunes the horizontal to the flyback/deflection circuit, kind of analogous to the safety caps in US made sets. They are obsolete - but a good 715P or 716P (polypropylene film/foil) Orange Drop will also do.

Damper diode part number is SID30-15 on your set - Sony recommends replacement GH3F, Sony Part number 8-719-305-15, also the newer RS3FS diode, Sony Part number 8-719-312-71. ECG/NTE 506's WON"T work. Save your money.

If your SG-613 is good, then I'd recommend finding and replacing all Electrolytics in the Pwr supply and Horizontal - typically on the "VH" board. The 4.7uF 160V and 250V caps cause the most grief.

SG-613 Testing:http://www.talonix.com/images/TestingSG613.pdf

I finally pulled the back.

This set uses the SCC-121B-B chassis and a 520KB22 CRT. To avoid dismantling nearly the entire set to find out the CRT type I used a bright light and inserted an old car inside mirror glass between the degaussing shield and CRT. Even then it was difficult to get light and mirror positioned just so to read the code.