and appreciate your postings. I understand that you are basing your opinion on present circumstances which have nothing to do with the original design philosophy. The "Super-Grade" was designed for ease of repair by the fact that it does have a removable sealed valve unit. It was intended that the unit could be removed and sent to the factory for exchange/rebuild. As pointed out by Trevor above, "at the time it made a lot of sense."
To answer your questions; Yes, I have removed/opened/repaired several sealed valve units. It does not take a rocket scientist, just someone with mechanical skills. I followed instructions found on this forum to repair my first one. I purchased the seals from JG Airguns and made the necessary tools. Since then, I purchased several parts and tools from another collector, which is where I got the pump piston pictured on my site.
Saying that the "Super-Grade" can't be repaired today is simply not true. In addition to myself, there are at least two other well known gentlemen in the country who repair them. Yes, the owner will have to send the rifle out and the cost will be more than most other pneumatics, but the end result is well worth it IMHO, and I hope you can respect my opinion.