Yamaha GH actions require the insertion of a “rod” (as it’s referred to in the service manuals). Yamaha sells a specific tools—specifically part TX000671 (VCN03010) during disassembly. The rod blocks the hammers, relieving the pressure on the contacts and contact circuit boards. You can then easily remove the contact boards, or perform other service.
The Official, Correct, Boring Solution
You can purchase Yamaha’s official part VCN03010 (formerly TX000671). It is a steel dowel, of suitable length and diameter to conveniently fit between the hammers and the frame. It’s exactly as perfect a steel dowel as one would expect from Yamaha. However, it is nonetheless nothing more than a plain steel dowel.
The TX000671 Alternative!
One day, when working on a CLP-645, I found myself in a pinch, and used an improbable substitute: The 48-inch Orange Ground Mount Reflective Rod (or common driveway marker)!
Driveway markers are not only the correct size to fit nicely in both the Yamaha GH actions, blocking the hammers, but I find them easier to use. The marker slips more easily between the hammers and the frame because of its tapered, pointed end. It’s made of fiberglass, so it’s less likely to cause unintentionally scratches. And in fact, the far end even comes with a ready rubber bumper, just in case you lose track of it and whack a wall with it!
The TX000671 (VCN03010) currently costs $187.0 to the public on Yamaha 24×7, whereas the trusty 48-inch driveway marker costs $3.27 at Home Depot (prices as of 9/9/24). It’s an option worth considering! I now have a small stack of these in the corner of my shop, just in case I need one unexpectedly.
I’ve verified that this does, in fact, work on the newer GrandTouch actions, such as the GrandTouch-S in the CLP-745.
If you’re working on a GH3 action and are looking to play Dr. Frankenstein, take a look at my article about generally equivalent replacement GH3 actions.