This is an STX model? I ask because you say the specs are rating the rigger for a 15lb weight. Ever since the re-design they have been able to handle 20lb weights. If this is indeed the older HS rigger it's got to be 6+ years old. Is that a quote from Cannon, or Tony who repairs them in Buffalo?
Let's also not forget Cannon was bought by Johnson Outdoors in late 2005. They inherited some issues from the last company, and in a couple of years they totally redesigned the downrigger lineup.
The new line up, which is going on 5 or 6 years now, from the 5STX to the Digi-troll have a less than 1% failure rate. We run 15lb weights 3-4 days a week on ours, and many days in the Spring/Summer a 20lb weight. We have had 1 DT blow a board in 5 seasons.