I used to pound the male part with a hammer to flaten it so it would fit tighter.
indij13
February 2010
I suspect you can't fix the actual snaps. Replacing isn't difficult if they are sewn on. Finding the place to buy them. can be a challenge if you don't live near a good sewing shop. Obviously they are available on line but the postage might be prohibitive
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix general clothing.