P38 1995 with Clarion Diversity radio PRC 7618 / PU 9836A. 'Code In' appeared but I was unable to actually enter any figures so I sent it off to Tom at GB 4X4 Radios in UK (formerly Roverville) who had repaired it in 2012 and who I found is very knowledgeable and helpful. Unfortunately he was unable to trace the fault and said, as far as he was concerned, it was unrepairable and he couldn't offer any replacement. That was a set back because that particular model is rare and the alternative PRC 7617 wont work in my early vehicle.
However whilst doing a bit of research I came across the Clarion Service Centre in UK and sent them an email at [email protected]
. Received a prompt reply from the Service Team Leader saying they were reluctant to take in units that have been repaired by 3rd parties but mail it to them. There would be no charge for diagnostics and they would give me a quote if it was repairable. After they received it they sent me a comment saying it was a bit of a challenge but they had found the fault(s) and gave me a reasonable quote including installation of flying lead with 3.5mm jack for connection to iPod/iPhone/MP3. I was very pleased to get it back after a couple of days in full working order.
Hope this might help somebody facing a similar problem.