no one replaces grommets for free they do have a cost, although the labor is very minimal
don't smear butter all over the racquet thinking it will make things easier... it won't.
If you've already told her you'd do it for free, perhaps tell her the next time you'll have to charge and keep your promise this time.
Thats what I was thinking, but she told me she would give me some money.
yea theres always a charge. in fact, replacing bumperguards can be very tough. just try to do a babolat pure storm ltd. the wilsons are not too bad. be patient, and it helps if you have the tools, such as awl, pliers, etc. usually to take it out you use the plastic handle to depress the grommets from the inside. then once you get afew you can ply the rest out pretty easy.
installing new ones is tougher. its tough to describe it in text, so if you have a specific issue let us know
Use a blow dryer to warm up the grommets before pulling them out.