I have read enough ads fot vintage equipment to list the following statements sellers use.
You can always rely on the phrase sold "as is , as pictured" with no warranty expressed etc. with no returns accepted . It is a vintage piece, as such, there may be issues which are not readily obvious. Then say something like- that it may not perform well in your system, which may damage the amp/ Etc.
Then tell the buyer as is happens to performing well and intended. Also tell of the recent overhaul anywhere you want to.