Hi there! It would be the best to look for shorter grub screws. They may need to be purchased from a music equipment or any related repair shop in your city. Look for any relative info on the size of the screws on their websites. Besides, you could check if replacements parts are sold at online stores such as https://www.scrooz.com.au/. Keep in mind that it’s essential for you to use the correct screws. If this doesn’t work, you may try to grind the existing screws shorter. I hope my advice will be helpful.