I bought mine in the early 1970 time frame for $29.95. They are a bear to put back together, but when you learn the trick of the positions of the various parts. It is not that hard. Like everything, experience makes things look easy.
If you bought it in the ‘70s it would be a Mark I. I have never had any issue with detail stripping, cleaning and reassembly. I guess the Mark II, introduced in 1982, has a few extra kinks that seem to cause problems.