Overheating Blower Connection at Fuse Panel

[Classics Fan]

I recently posted about a problem I was having with the cigarette lighter in my 1971 Jimmy Custom with AC. Related to that post and subsequent thread I discussed how I found the HVAC blower connection at the fuse panel melted. (I had begun smelling something hot just previous to this when the blower was run on high). I chalked that up to a bad/corroded/oxidized connection and replaced the melted female spade connector and short length of wire that showed signs of melting, and added a 20A inline fuse at the panel connection.

Fast forward to yesterday, the first time I’d driven the vehicle after the work described above. Within 10 minutes or so of the blower being run on high speed I caught a faint whiff of hot electrical but it seemed to go away. However when I returned home and looked I found the new fuse panel connector had a dark spot on it and it cracked when I pulled it off the fuse spade. It only gets hot with full voltage to the blower on high, not on lower resisted voltage at lower speeds. Also, the 20A fuse did not blow. I’m confident the connection to the fuse panel was tight.

So my question to the folks who understand electrical much better than me, what can cause this? I assume high resistance in that circuit? Blower motor? Or something else?