What surprised me was that there wasn't any buzzing when I started to play it. Buzzes can be caused by a whole host of things, but are usually caused by open seams or string grooves in the nut that are not appropriately sloped and even fingerboards which are not fully glued down. In this case, the fingerboard was tacked down in 3 small spots. In spite of all the shortcuts I took to get the cello temporarily playable, it sounded great.
This is in contrast to some recent repair work I took on. While my standing rule is not to do repairs for those I do not know, I made an exception to address a cello that had recently been purchased used from a major big box store. It came to me with an incredibly tight soundpost and open seams on the upper and lower bouts of both the top and back. The A string had chewed through the nut groove to the point where it was resting on the fingerboard. The fingerboard had zero scoop and in fact it had a hump under the C and G strings toward the nut end. Humps are notorious for causing buzzes. The nut was also loose. I corrected all these problems and guess what? The client is hearing a buzz that was not there previously. After 12 hours of additional troubleshooting including consultation with another skilled and trusted luthier, the matter is still unresolved.
In this modern age, although there is a large body of knowledge related to stringed instrument function, sometimes we are reminded that there is still an element of mystery related to these wooden boxes.