Re-proofing leather sailing boots

There are various ointments you can apply to leather to improve things, but often the main ‘waterproofness’ comes from a breathable membrane underneath the leather uppers, and once this goes that’s yer lot really.
 
Yes, anything like that to put some oil or wax back into the leather.
My Orca Bay sailing boots are letting the damp in. Has anyone had any success re-proofing leather sailing boots, and did they retain their 'breathability'?
my atberg shooting boots ger ledder wax from ebay
 
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