I do not remember hearing of a recall, however there was a piston design changed. The original pistons have the same stem diameter from tip to piston head. The newer pistons stems have larger diameter near the piston head.
I'll try to dig up more information, but it sounds like the LDS is blowing smoke. If the piston was recalled, the regulator would be recalled.
Hopefully DA Aquamaster will weigh in. Here is a quote from a post he made on that other board back in 2012
....."I'm not sure when Scubapro switched to the stepped piston in the Mk 5, but Scubapro has created some liability issues for some shops/techs by recommending the earlier style pistons no longer be used. Should one of the older straight stemmed pistons fail or cookie cutter the seat, the liability for the tech and shop is now pretty large as they are violating Scubapro's service clinic recommendations by putting one back in service. Since replacement pistons are no longer available, some shops will be hesitant to return a Mk 5 to service with the early style straight stemmed piston."
For the thread, see https://www.scubaboard.com/community/th ... ts.424787/
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