Haha I know that feeling!
On 5x mag with a 40mm lens you should get an 8mm exit pupil, which is the maximum amount of light your eye can take in. Sounds like the Hawke just isn't cutting it with light transmission.
I've had a look through a couple of old tasco scopes, the world class model, and the lenses were superb- I think they are a similar story to the nikko gold crown, they just don't make them like they used to.