The Lotus Grand Tourers

I think I need a replacement RPM sensing relay.
This is the relay under the bonnet, next to the ignition amplifier. Lotus part number A910E6757F.
The throttle jack solenoid kicks in as it should when the air-con is switched on/off - so I take it that the solenoid is working OK.
However on over-run, when I take my foot off the throttle, the throttle jack solenoid stay energised, with the revs staying at around 1900 and never drop back to an idle of 950. If I remove the connection to the RPM Sensing relay (throttle jack relay) the revs drop off just fine.
The relay has 'BOSCH 0280 230 103' on it.
From various online searches it looks like I could also use Bosch part numbers 0280 142 020, or 0280 142 001, or a Saab 9346 206.
However I can't find anyone selling one of these.
(Lotusbits don't advertise one on their web site - but I'll contact them next week).

Mine did this when setting up the carbs, if you adjust the bolt that the solenoid touches to open the throttle, so that it doesnt rev so high when its activated the solenoid should switch off.
if the revs are too high when the soloniod is activated it does not switch off,
I think the solonoid should only increase the revs to about 1200 rpm.

That's done it. Thanks.
It's quite sensitive. Just a fraction of a turn either sets it running so high it never drops, or such a slight rise that there is a risk of stalling at idle when the air-con is switched on.