So no Semiconductors failed then? Excellent Work Sir !
Hundreds of units must have been scrapped due to these resistors failing.
Amstrad products used to fail for the same reasons...................... The corrosive Glue
I used to repair Amstrad Satellites till 3 AM sometimes as they dropped like flies just after the Guarantee ended
BTW standard 1/4 Watt resistors with legs could probably be used if there is space.
So don't worry about trying to source the exact surface mount components
They will solder on the the SM lands.