If your joints are leaking, do not attempt to seal them as this just doesnt work. If it does work it will only be for a short period of time, costing you even more money if you have to get someone out to do the job again.
The best way to fix this problem is to replace the part. New seals, new part. It’s as simple as that.
Get it done and get it done right by Gutter Mate Local Wolverhampton