I have had spotty results over the years with CA glue. It's no so dry here, so I don't see that many pianos with dried out pinblocks. I believe that one critical factor is the age of the glue and its viscosity. CA glue has a shelf life if you open the bottle, and is better kept in the 'fridge if you're storing it.
Having said that, I have had instant successes even on upright pianos just wicking the glue on top of the pins. And I've had failures on grand pianos soaking the pinblock. Sometimes it seems that the more glue just lubricates the pins more. I have deliberately not used any hardener for fear that the glue might not penetrate the wood. But I have changed my mind on that. The very thin glue does penetrate more than we expect it to, and farther. I have removed pins and spread glue on them, then used hardener and reinserted the pins with good success. They were not looser by turning or pounding them in. I have also swabbed the holes with glue, and that also worked, with or without hardener. But I am not shy for using hardener if they don't immediately tighten up. We know that often the pins that are loose are in areas of the pinblock that are narrow. A cracked block is another matter. Sometimes CA glue doesn't hold, sometimes it does. Pounding them in doesn't solve the situation if you have a cracked block, it often makes it worse.
A recent job on an old Bosendorfer I had to use CA glue on. The bass strings were not tunable, but I had to replace them anyway, so I removed the pins and put glue on them with hardener. I didn't want to pound them in, so I just turned them. It worked very well. I also put some glue on other pins that were acceptably tight, and they got too tight! I regretted that, and it happened like that before. So I guess if it ain't broke, don't fix it.
After all this, I don't believe using larger pins is a good idea in an old piano, unless you're restringing it. If the piano is fairly new, ok, put new pins because the block is likely going to be strong enough. But going to a larger pin may backfire if you end up with tight and jumpy pins. If the wood is split, bigger pins won't help. If the wood has dried out, using CA glue can fix it, even if you have to remove the pins. You might break the becket in the process, and probably should just cut off the old one anyway. At least youi'll have a tunable piano. Does it devalue the piano? Maybe, but it'll be much more valuable than a piano that's not tunable, and you don't have to install a new block. It's a band-aid for sure, but it's a viable alternative to rebuilding/restringing.
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Paul McCloud, RPT
Accutone Piano Service
www.AccutonePianoService.compavadasa@gmail.com------------------------------