Simon, I haven't forgotten about your running gear - in fact I spoke to Al-Ko only this morning (about something else) and I did ask about availability of parts for your 1970s chassis set.
They would require all the information from your axle ident plate, as this is the only way of calling up the bill of materiels for your build.
The critical field is the build number which will (hopefully) be in the format of LExxxx (x=4 or 5 digits)
Other info from the plate will help too.
It may be easier to read the plate if you remove it by drilling the rivet(s) off - but take care not to slip with the drill and obscure any info.
Hopefully you can read the data off the plate, but if not you may have to remove the faulty items and we may be able to identify them from pictures, measurements, etc.