[pianotech] woodworm in soundboard

[svmpianostemmer]

Hi,

Recently I was asked to do a complete restauration of a Erard grand  
piano from 1860.
The piano is worth to restore.
Biggest problem are the woodworms. Most parts who are affected by the  
worms can be replaced or treated.
What I'm not sure about are the wormholes in the soundboard at one  
side of the board. You can see the holes
of the worms in the board only a few inches from the side.

How could I be sure the worms have not been further than what can be  
seen by eye?
A replacement of the board is not an option. There is still enough  
crown.
Will a treatment of the wood be enough to ressolve the problem?

All advice is welcome

Stephan Van Meirhaeghe