Am I missing something here ?. Seems like you're doin' a lot of faffin' around for very little.
Why not get the clock professionally refurbished where such a procedure is quite excepted. There are many competitive clock restorers in the UK alone and, specialists in aircraft gauge refurbishment where a Smiths or Jaeger dial [if that's all you want done] would be commonplace. At least talk to a few professionals, might save you a lot of headaches in the long run.
i don't understand why you would call a 15 minute job which is basic maintenance faffing around. Do you throw out an engine when it needs an oil change? Really best if you don't contribute if you do not have anything constructive to say. Most people want a cost sensible solution that if possible retains the original