Firstly are you sure that's a Solar? the Solar's had orange cab's and less angular windscreen, the older DH's had the white cabs and quite an angled front screen i'm sure, if it is a Solar then the Solar machines are like a lot of the older machines, "built to last not Built to price" easy to maintain with less complex electronic involvement that said, because they weren't as popular as the bigger names at the time of first production, there isn't the availability of parts and there will be a few parts that are obsolete, ones that seem simple but can terminate a machines life.
EDIT I was getting my early up to Solars III mixed with later -V machines so it is more than likely a solar
