Any electrical experts able to identify suspect areas on the circuit?
Could be anything.
Although i'm not remotely an expert but i'd personally see if the electrolytic capacitors (black, white stripe; C3, C5, C4?) are bulging (look side on, can bulge top or bottom, not always easy to tell) and if so (do it any way to be honest), replace them as it's a cheap part (pennies) and they're fairly common to fail. Just make sure the replacements are the correct values.
Similarly with the ceramic (blue; C21) and film, i think that's what it is, capacitor (red; not marked).
After that it's a toss up between diodes, resistors, pots, failed IC (DB1 is a rectifier; no idea on the other) or the sensor itself and at that point i'd either be trying to shoehorn something else in it's place or see if i could hunt down a replacement board (STMicroelectronics maybe from a quick Google).