Grab a glove or a tee and put this under your triceps muscle of the arm you’re are putting with so that you have some connection with your upper arm and chest. This encourages you to start or continue to work your shoulders within your practice.
I like starting from around 1.5 meters. This gives you enough swing but will not get to out of control in the early stages of you getting the correct feedback.
Hit 10-20 putts with certain grips seeing which feels the least moving parts in the wrist joint. Which is the easiest? Which position allows your shoulders to pendulum?
Now swap hands and do the same line of questioning!
I would do this twice with both hands just going back and forth seeing how true strike of the putter. This also helps build control and the muscles and tendons in your arms will fatigue so once that has happened its time to have a break. But don’t just do this once. Keep readdressing it over a two week period. You will be amazed how much control you get.
Finish each session going back to some longer putts and doing this with both hands. This is the part where you try and see which hand is better at dominating. Each player will experience different feels and will have to troubleshoot their way through to a solution that they can lock in and stick with.
One of the biggest mistakes I see is people not letting things bed in enough. It takes time for the body to bed a habit so patience is the key!