If an art work in the care of a public institution needs repair or refurbishment (cleaning usually) it is sent off to the conservation department. The people there are trained to restore objects to as close to their original condition as possible and, if they do have to changes, to make them in a way that can be reversed later if necessary.
Before the conservators came on board the person who was usually called in to repair or refurbish was the artist. But there was a problem. Artists move on and often what seemed to them to be a good idea at the time the work was made has been superseded by new ideas and new techniques. And so when they get their hands back on that painting with the bird flying through it to restore, it could end up with two birds or (even more alarmingly) no birds at all. If the bird was why you bought the painting in the first place this is not necessarily good news, no matter how brilliantly the ‘restored’ work had turned out. In general, it's safer to stick with conservators.
Waharoa, the large carved wooden gate made by Selwyn Muru in 1990 for Aotea Square, has now reappeared having “been sent to the artist for extensive refurbishment.” Those who liked it as it was are in for a shock, and those who enjoy change will find it changed.
Images: Left, before and right after, complete with guitar and sax