Remove 'all' the old sealant

[Andy Unique]

Hi. 2 connected quick (hopefully), dumb (probably) questions, please:

1) I have a shower which I installed a few years back and now needs resealing due to mould starting to show. The advice always seems to be that you must get all the old sealant off first, except I know I won't be able to do that. When I installed the shower I put sealant between the tray and the waterproof backer board, and then I put sealant in the gap underneath the shower panels when they were installed (diagram below). Obviously the best I'm going to be able to do now is to pull/cut some of it at the front free (the bright red bit).

I don't see any other option, so I guess this must be the right thing to do but just wanted to check before I spend the time doing one of my least favourite DIY jobs of all time

2) Again, connected to the 'remove all the sealant because new stuff won't stick to old stuff' advice.. What happens in the corner/near the U channel where the shower cubicle is mounted to the wall? That has a load of sealant behind it too, presumably it must be OK to just cut up to the corner and assume it'll make a waterproof join? I can't imagine people dismantle their showers every time they need a bit of sealant replacing?

Thanks guys

 

[denso13]

Yes, remove what you can till the edges are clean the re-apply. Use a good quality silicone.

 

[jj4091]

If you use black mould cleaning product you shouldn't need to remove the sealer