L 322 with no low range

Hope someone can advise with this, I've got as far as I can. 2003 TD6 auto with 111000 miles. Car shows Trans Failsafe Prog on display, drives perfectly changes gears normally but will not select low range. In neutral, pull back switch, nothing happens at all. I have had the motor off, cleaned commutator and powered it up on bench. Motor spins over fine, put multimeter across pins and got variable resistance as motor spun.
Prior to removing motor using switch would cause lo-range light to come on but nothing else, now that has stopped. Double checked connector, pins and sockets are all bright and clean.
The previous owner had some problem with this about 3 years ago, fiddled with switch and apparently the whole transmission locked up.
I apologise if this has been covered before but there are so many threads on here I couldn't find a a relevant one.
Thanks in advance.

Is there power? If it was a P38 (I know it isn't) it could be GB ECU

I would have said it is the Transfer Motor Switch Pack - these are a common (and expensive) fail item....trouble is the switch pack isn't available seperatly and a new shift motor is £400+....

The problem is the plastic surround gets brittle and breaks away....there was a thread on RANGEROVERS.NET HOME about a chap who was trying to mass fabricate new plastic surrounds...a search on their forum may give rise to this!