How to assess whether it is better to repair or replace a wobbly spiral staircase?

I've worked on a wobbly staircase before. I drilled 8mm holes into the top and bottom of each spindle. Inserted long 6mm crews, this tightened it up. Then filled each hole and sanded when dried. Then re glossed it.

Hi Nat, when you say Modular... is it timber modular where each step is still supported or a metal one where there is usually a central pole and each step is slid over it. and when you say wobbly... are the steps wobbly or the balustrade wobbly. if the steps are i would really look at where they are connected for splitting as this would be a big safety issue if it should split completely. I would definitely advise not putting any strain or using them at all if you can help until you've got professional advice if this is the case.The balustrade or any hand rails are a lot easier to fix than the steps. Without looking at the staircase its unsure to say especially with regards to it being a spiral staircase as you could have more of problem safety wise than we could only guess at on here. I would definitively suggest seeking advice from a staircase company, remember they can quote you to remedy the problem and find it for you with a quick visit usually free. You can always cross reference your findings back here to make sure there not pulling your leg so to speak. Kind Regards Craig