Working my way through the Heathkit C3U and all the caps on it check out OK but the resistors have drifted massively thus maybe accounting for the differing voltages so last night I made a list of what I needed and ordered from a local seller on eBay. Only lives a couple of streets away and today, he kindly popped the order through my letter box. I think that such excellent service needs to shouted about when it happens, so here goes, the seller goes under the name of MS Graphics. I have used them on a number of occasions and can highly recommend them.
Anyway apart from the resistors drifting, I also noted some changes from the schematic, these being on 5V, 25V and 150V settings which schematic shows should have 2.2K, 8.2K and 22K fitted but actually had 1.1K (giving me 3V), 37.3K (91.5V) and 6.9K (108V), so it will be interesting to see what the end results will be once the new ones are fitted, all are 1%, old ones were 10%. Photos to follow.