I don’t want to speak too soon, but it does seem the spam brigade has stopped, for now. Been checking the forum every day since last week and the last few days I’ve not had to do any whack-a-mole.
I think Adam’s adjustments to the codes have taken full effect. I think his explanation was that the captcha system could somehow be circumvented, so whatever adjustment he did must of closed that and hence the dramatic drop off in spam.
I’ll keep checking once a day though since spam attempts never stop.