I created a video for those that have the 299C clone amp. The procedure is identical to the factory procedure and applies to the factory originals as well. Here I'm using a Fluke meter. I also have the procedure recorded using the scope and will revise the page to include that too. The results are, for all intents and purposes, identical.
https://northreadingengcom.ipage.com/Video_Library/299C_DC_balance.htm