Actually, funny you should mention that.... about Roland maybe having re-engineered the part.... Because they did.... I contacted Roland Canada (PLEADING them not to just dismiss my e-mail by telling me to contact Roland in Japan.... )
As an aside, Japanese customer service is completely USELESS! The entire conversation is spent in "super-polite mode" where it takes 5 minutes just to say "pardon me." It's more like: "This is completely inexcusable, most honorable one, and I know I'm being terribly rude by asking for your assistance, but would you please be kind to me and offer a reply to the question that I'm so humbly about to ask?"
Anyway, I digress. Yes, Roland HAS re-engineered this design. They just returned my e-mail (quickly too, I might add) and advised that I replace all 88 "key hammers" (that's what they're called) with the improved ones as soon as possible. Now I'm trying to work out the cost and feasibility of this exercise.
I tried Roland Japan (because Roland Canada said they will not ship parts overseas) and when I called, I was told "no way." Apparently my request doesn't follow the "Roland Concept" which neccesitates having a super-human Roland Technician be dispatched from Tokyo all the way to my home in another prefecture, and he, and only he, with his skillful, surgically-steady hands, will replace the hammers.... For an ungodly, exorbitant cost too, I might add. (You think I could ooze any more sarcasm here?) Well, you can imagine that I told them what I thought of THAT idea.... So, I'm requesting Roland Canada to get me a price so I can ship it to a Canadian address. I'm more than capable and willing to do the work myself, especially seeing that the piano isn't under warranty anyway.
In the mean time, not having a piano to play on (especially when you're supposed to have a performance in 2 days) is like being a skiier with two broken legs. So, I went to the hardware store, picked out the most expensive "superglue" made for bonding metal to plastic that I could find, and laid it on.... I reinforced one hammer that looked like it had maybe another day to live, and the one that was completely broken. The glue seeped into the gap between the plastic and metal, spreading a fine film over most of the surface. I let everything dry for 24 hours, and just finished examining my work... It looks quite solid. I'm sure it's likely going to be more brittle now, but it seems to have bonded very well -- in fact, better than I expected.
So, I've reassembled the piano with the repaired hammers and just finished testing it out with some pieces. It feels right -- no different than any other key, and quite solid. So, for now, I'm happy. But likely during the winter holidays, I'll take the time to either replace all the hammers (if Roland gives me a favorable reply) or reinforce them all to hopefully avoid future breakage.