Jim, “you can try at home” to change one triac and one resistor as well, and problem GONE!!!
On manual it shows wich triac corespond to your problem (your case area3): change that triac and 220 Ohms resistor (marked 221) from his gate (right pin wich is connected thru one thin path).
P.S. depending of electronic you can find there, instead of triacs (Z…), ACS… do not switch themselves because do not work at least you know how to connect correctly.
Also check before if ULN2003 isn’t burned out (exploded). In that case more surely processor is out also…