Quoted from matiou:Thanks! I confirm your memory is right... However Q18 appears to test ok from basic DMM test... Anyway I'll order a transistor and a decoder and change both... but I wait to accumulate issues before placing an order, to save on shipping. I'm sure I'm going to need more things in the coming days!
Big daddy sells kits on ebay for $12 shipped that has all the transistors, socket, decoder and 6 upgrade resistors.