Karl
Karl,
What is the serial number on this machine, please?
If it is a 1970 or older machine, the nameplate will be found riveted on the bottom of the motor housing.
But if it is 1971 or newer (which I assume is most likely), then the nameplate will be in the form of a decal affixed to the back of the nozzle casting.
Example of serial number: 37J-A-79185. The first digit in the date code is the year of the decade (3 being 1973), the second is the decade (1970s), and the third (the letter) is the month (September),
~Ben