Cat 315bl- Swivel Disassembly / Repair Procedure

Hello All, Tracking on my 2001 Cat 315BL excavator is a bit problematic. SN 3AW02476 with 9,500 hours. Seems to lack power/consistency when it comes to turning and or trying to move one track by itself. Both controls forward or reverse, seems to move along ok, but it does drift. (seems that is considered normal??) Hi speed works fine as well when in the straight mode both controls being operated, same issue when trying to turn, responsiveness gets compromised. Engine does not seem too lug down, the machine digs very well, so not thinking a pump issue. Based on reading quite allot of posts and experiences on the topic. It occurs that I need to consider the swivel joint and where I should begin. The removal of the swivel sounds as if it is pretty straight forward, a bit messy, otherwise not too bad? Wondering if anyone could share a disassembly/repair procedure? I would like read the steps if possible. I do have a parts book and looking at the breakdown should be helpful. Earlier this year, rebuilt both final drives. Inspected and resealed both drive motors, replaced bearings as well. Piston group looked like new. Most recently had to reseal the swing motor, changed all filters as part of that process. Hydraulic fluid was very clean and no foreign material noted anywhere that I had access too. The tracking/traveling issue has been consistent, not a new development. Thank You in advance for any and all assistance. Nick