In article , Incubus
wrote:

On 2021-05-09, Eric Stevens wrote:
A few weeks ago my trusty Nikon SB-600 flash unit stopped working. I
sent it off to the Nikon service agent (700 miles away) and they
reported that after they cleaned the battery contacts it was working
OK.

I tried to use it again today and everything was working properly -
right up to when I try to take a photograph. All the right things
happen in the window, including the little red light blinking as the
capacitor recharges. But no flash.

The problem is probably the flash but I want to prove that on another
camera. The nearest suitable camera that I know is some 30 miles away,
right through the heart of Auckland. The owner works rather extreme
hours so it might be a week before I get to try it. In the meantime I
would be interested to hear from anyone who knows the workings of
Nikon flashes. What is the most likely problem?

They are so cheap on the second hand market (which is the only market for them
now) that you might as well go to mpb.com and get a replacement with guarantee.

that won't fix the problem.