The Roomba thought something was always in it’s way on the left. I found a replacement board on-line for $15 (that tiny green thing a little bigger than my index finger’s nail.)
After a lot of disassembly, I got to the old one and desoldered the very small wires attached. I have never soldered something this tiny before, but got the four wires in place and soldered on the new board. Reassembled, held my breath, and tested. Our Roomba is resurrected!