A long while ago fear that the ‘new transistors’ would prove fragile led to them being fitted into sockets in a lot of newly designed complex systems and test equipment (hey it worked for valves)?
This resulted in unreliable equipment and a standing order to the repairs group to jiggle all the transistors until the fault often cleared without further action.?
The transistor sockets soon disappeared from production and reliability improved markedly?
if the BS170s ever do need replacement you’re going to have to remove and replace them all. ?Use very fine wire cutters to snip the leads then pull the leads of each transistor out one by one with tweezers. ?It’s quite simple?
Bruce Akhurst