The only way to remove dens from under a saxophone guard is logically to get something under the guard and push up the dent. Regarding dents in or next to guard caps and strips, please take a look at our tutorials that have to do with boot jobs. We have put up step by step photos of several different operations that should be help to you. Also keep in mind that on German tuba guard caps there may be air space between the dent and the actual brass of the boot. Attempting to remove dents from areas of large guard caps can result in distorting the circumference of the bore.