PORT Adelaide young gun Miles Bergman has had a second operation to stabilise his right shoulder after an issue arose with the initial surgery.

Bergman had a revision of the Laterjet procedure, after a routine check revealed a surgical screw from a previous off-season surgery had become loose.

The 20-year-old returned to training with his teammates at Alberton on Monday to continue preparations for season 2022.

Meanwhile, general manager of football Chris Davies revealed that a chunk of the team were out of action due to COVID-19.

"We currently have around a quarter of our squad in the AFL's health and safety protocols," he said.

"Our players, just like the general public, are going to impacted by COVID and we know that number will go up and down throughout the season."