Yes, Paul, that is correct.
They had to open the smokeboxes and bore the flues with augers. The augers were part of the fireman's tools, which also included a clinker hook and a rake. These tools, or parts of them are visible in almost every picture of the left side of any C&S narrow gauge engine. They hung along the outside of the coal bunker, and across the top of the coal gate at the front, and sometimes can be seen on the running boards in front of the fireman's side of the cab.
Boring flues at least once, and sometimes as many as three times was part of a days work for firemen on the C&S.
Ah, the good old days!