Ah! The North orientation marker. I well remember a night watch with CJF. The weather was heavy rain with low cloud and a strong easterly wind. I was doing the sequencing on the AR15 and Colin was doing the SRAs on the 430. The temperature began to drop and slowly, the heavy rain turned to snow with a consequent drop in visibility. There were several aircraft inbound and we seemed well set. Suddenly there was a bang as the Xpelair ventilation fan flaps slammed shut and a flash and whine as everything wound down. Within seconds the power reset and everything rapidly recovered except for the 430 which, with a loud clicking, started to automatically 'North align'. The aircraft on final on the SRA was sent around but was there time to get the 430 set for the next one? Yes! Just. Then, at around 2nm from touchdown....Bang! Another mains spike...Wind down, wind up...Another North align and set up...Go around! This repeated regularly about every 10 minutes or less until all the aircraft on approach had been forced into a diversion decision.
Personally, I liked doing SRAs. They really were like Marmite. Some ATCOs enjoyed them, others really didn't. Also, I really can't imagine ATCOs being allowed to adjust a radar in the way we were with the 430 in those days. When I subsequently went to work for NATS the Tels guys were amazed we were allowed to change the ILS around! However, as in later Luton days there were no Tels engineers on duty at night there was little choice in the matter.