so far, OK
... But when you try to say evolution is NOT random (IE, designed or something) ...
"not random" isn't the same as "(IE, designed or something)". It's just not random; some combinations of genes favor survival and reproduction, and some don't. "The race is not always to the swiftest, but that's the wy to bet."
... they'll say no, because the thing natural selection acts on is random mutation. ...
True enough. Evo itself has both random (genetic combinations, mutations) and nonrandom (some are better adapted to the environment than others) components.
Is a casino a random process? To the gamblers it is; to the owners it's completely predictable business. See, it can depend on the scale at which you're viewing the process.
It's a cute little catch-22!
Nope. Catch-22 was a contradiction in the Army's rules; the fact that life has both random and deterministic facets is not a contradiction, it's a fact of life.
I think I said that.
OTOH, just because scientists haven't come up with a change agent other than random genetic mutation, doesn't mean that's the answer.
Yes it is. Not random means there is a aim, reason, or pattern - which is not true for Natural Selection. NS has no aim, no reason, no pattern and nothing to apply an aim, reason , or pattern.
Natural Selection is little more than an observation in the past tense - it is not a force that has aim, reason, or pattern therefore it is random.
I am guessing some Darwinists find comfort in thinking Natural Selection is not random?