"I'm told the machinery that gives the pole its wobble may be doing too good a job at giving it a wobble so it might be putting the pole under stress but that's just part of the re commissioning of the sculpture that we're doing," council spokesman Richard MacLean said.
Local engineers and glass fibre experts will assess the pole and make a call on whether the cracking will get worse and further strengthening is needed.
"We might have to recalibrate the machinery just to calm down the sculpture a little bit.
"The last thing we want is for it to fly apart and land on someone's head," MacLean said.
The sculpture was put back in place in the middle of last year prompting then mayor Justin Lester to warn would-be climbers "don't be a dick".
"I just want to say to everybody we're installing a new policy, which is don't be a dick.
"Don't even think about jumping on the Water Whirler," he said.
A bystander filmed Macdonald scaling the pole as it bent under his weight, until it snapped off at the base, hitting him on the head as he plunged in the water.
He suffered a brain injury that came "dangerously close to being fatal", according to lawyer Carrie Parkin.
