gurgled happily, sounding much like they were saying:

The trick is to find the first point *downstream* which *isn't*
blocked, and then rod in an upstream direction from that point.

And hope you can get out of the way in time!

SEP...

If you try to rod from one that's full, you can't see where the
outlets are - particularly if it's deep (mine are all 2 metres or
more!)

I always try first from upstream, usually you can find the outlet if
you've seen the manhole empty previously.

I'm about to go out and try to find the manhole cover that's somewhere
under the front garden which is somewhere under Friday's snow which is
somewhere under last night's snow.

I've seen someone covered in s**t having rodded a large blockage on a
hill from downstream. Not a pretty sight!

Indeed. I feel vaguely queasy just reading some of these war stories...