D peg slipping when tuning

Hi all,

My D peg keeps slipping no matter how hard I press into the cello when tuning. It doesn't happen on any of my other strings to it's really frustrating

I heard you can put some chalk or paste on it but that requires taking the peg and string out of the peg and that's way too complicated for me and I feel like I'll just end up making my problem worse.

My normal luthier is off ill at the moment so I can't take it to her. Can I take it to any music shop near me and see if they can fix it? Would it be costly? (I live in the UK btw)

Any advice would be really appreciated :)