I literally just redid my 27.5er hardtail a couple hours ago. Had to redo my rim tape so the valves had to come out. Resorted to pliers on the front valve when reinstalling. A little leak is fine since you can bounce it around and get the sealant to fix it but it was leaking like crazy till I got the pliers out. I used a new valve I had bought for my road bike on the rear and I think I'll be replacing all my valves with that style. It has a better designed nut that you can get tight by hand and works with tire inserts which I plan to run on the rear.
https://www.amazon.com/gp/product/B0...TF8&th=1&psc=1
one I used but probably 500 other people have the exact same valves for sale on aliepress for $5 give take.