Hi Dan,
Considering that your serial number is 2510A, you need the correct manual. I posted an updated manual on the KO4BB site, so feel free to get it there. The change in voltage on the power supply rail was called out in one of the addenda also posted with the manual).
1) At serial number 2336A and above, the +15.7 V specification changed to +15.000 V. So, even though the 5335A is very forgiving, I would align the counter supply to that +15.000 V voltage.
2) IIRC, the procedure you mention calls for the interconnect cable to be removed, and for pins 1 and 16 on the A1 power supply board be shorted in order to bring up the supply (please carefully check my recollection). The power supply will not power on with the cable removed unless these two pins are shorted together.
I work on these units quite often, so please let me know if you have questions, and I will try to answer them. Congrats on acquiring a great instrument!
Regards,
Joe, KN5U
