I can imagine a lot of operators who had bought this model might have assumed they could replace the filters but were left a bit puzzled when they could not open the canister. I am sure out of frustration more than a few got broken or sawed open in an effort to change the filter. Perhaps this is why Victa decided to introduce the capped tops so operators could replace the filter inside and not the entire canister. If these were regarded as a throwaway item, I guess that might be why there are so few in existence today? It's the first one I've ever seen.
