I just read this thread with some interest and I have a couple of thoughts.
First, I don't think it is entirely reasonable to think that any manufacturer has the ability to maintain a stock of obsolete parts large enough to last forever. I'm not saying Bushnell did all they could here but, I think the jump to saying they didn't even ATTEMPT to accomplish this task is a bit excessive. Warehouse space is expensive and storing a lifetimes supply of parts that will seldom if ever be used is just not reasonable.
Second, according to the original posters story, Bushnell did offer to have him send in his binocular for a custom fitting -which he declined. Why? This seems a very legitimate method of addressing the lifetime warranty that doesn't require the company to use up a lot of warehouse space on parts that almost never will be used. Sure, it might take a bit longer than desirable for him to continue using his binocular but, the alternative is not to use it at all - ever.
Nyatt,
I readily admit that I don't know all the details but, it seems to me that Bushnell has offered a reasonable, good-faith option for honoring their warranty. I would suggest you pursue the matter and seek the appropriate "repair or replacement" as stated in the warranty (assuming you are the original buyer and are entitled to the warranty's provisions.) If, after doing this and exhausting all your available avenues, Bushnell simply decides to put you off, then come and tell us the sad story. Until then, you need to follow through and give them the opportunity to make good on their warranty's claims.