replacing mains powered smoke alarms

Just found out my mains smoke alarms don't work when I deemed to forget I had bacon cooking in the pan.  They test fine but I've done a bit of googling to find out the reason they don't work is they are too old and so clogged up with too much dust.  Anyone know if the connector that connects the mains wires with the smoke alarm is standard to all smoke alarms and it is just a case of switching them over?   Don't want to call an electrician out if it's as simple as that.