I don't have a rover 400, but...
I had a similar issue with a 1984 Ford Escort a little over 10 years ago that turned out to be some module attached to the side of the distributor. It cost me about $35 and was very easy to remove and replace. I can't recall what the module was called, but I know it wasn't a voltage regulator, or the coil.
If you can, add some more information about the vehicle and a better answer could probably be provided.
You can find a diagram regarding the installation of a replacement ball, on your Range Rover 400, at most Range Rover dealerships. Most auto-parts stores will have the diagram.
The Hydraulic clutch fitted to the rover 400 is a sealed unit and the only thing that you can do is to replace the complete unit
A Rover 400 can be purchased as a second hand vehicle from dealerships or online classifieds as it is no longer in production. They were originally sold in the UK and would be more commonly found there or in Australia under the name Rover 416i.
Remove the Fuel Tank
Filter is located behind the glove box
Under the bonnet by the battery it also works the horn
how often do i have to change the timing belt on my rover400
you need a new heater fan its burnt out
You should not bypass the relay. Repair the problem.
On the rover 416 the fuel cut off switch is behind the centre console drivers side, roughly behind the radio.
400 degrees
against the bulkhead, next to the ecu