I am making a screw-retained mandibular prosthesis and we are utilizing an 8-year old Astra 3.5mm implant along with four new implants placed by my oral surgeon. I accessed the .050 hex very easily, but cannot get the screw loose. My drivers started twisting in the hex, so I stopped and sealed the opening. I ordered a Zimmer SRT ( screw removal tool) driver but have never used one before. I also have a call in to my oral surgeon to see if he has experience with this. I don’t mind taking this on again, but I am seeking any advise I can get on making this work. Can anyone offer tips on loosening the screw and the use of the SRT driver? Thank you! I am having an issue uploading a photo , but wanted to get this out. I will try to add the photo as a follow up.