Thanks Ian,

There were existing fans and holes in the rear panel, and I was
just curious before replacing the fans. Both had become noisy and
I removed them without checking air flow direction.

The new fans blow air in and onto the heatsink, and there is a good
outflow for the heated air. I've run the unit into a dummy load for
some time and everything is working well now.

My only regret is that the original fans are no longer available
and consequently the restoration of the unit is not 'perfect', but
the TS-930S is a lovely unit and is now running well again.

Thanks also to all those who replied to my queries.

Irv VE6BP