I found a set of five of the "mini" Torx drivers at Sears for around $10 last fall. Craftsman. The individuals were $5 each, so it was worth it to me.
My 1670 is still going strong 3 years in, and though I haven't used it in quite the conditions you have, Delta, I think yours must have had a bad spring. Mine has been swimming in fresh water 100 times, it's been a hammer (actually, I usually hold it on the nail and stomp on it to drive the nail) and pry bar, and it's still going strong.
Also, you don't have to send it in for warranty repair. From here
, you can set the subject to "Warranty Service" and just list what you need, and they will send it to you free of charge.