Glue: Bostik Shower Seal
Cleaner: Meths, Isopropyl Alcohol
Method: Cut out the old silicone with a stanley knife. Clean surface to be sealed atleast 3x to remove body fat / soap. etc.
Tape around 5mm each side of the area to be sealed. Apply the seal with a caulking gun, smooth sealant using a wetted finger with a couple of drops dishwashing liquid in 1 cup of water.
Remove tape and give sealant atleast 12 hours to dry.