Just recently had the original HDD fail, so I decided to upgrade to a SSD and max out the RAM while I was in there. Was astonished at basically having to gut the computer to get to the backside of the logic board to upgrade the RAM. By comparison replacing the HDD was fairly easy and straightforward, the most time consuming part of the whole job was cleaning off the old adhesive from the foam seals. Once I got the drive restored I was astounded at the improved performance. The best bang for the buck I think is the upgrade to an SSD closely followed by bumping up the RAM to 16gb. If you do them both at the same time you can get by with using only one seal kit. Removing the logic board can look a bit daunting but if you take your time and follow the instructions on this site, you have an excellent chance of success. It’s well worth the $300.00 and time to do this as I figure I can get several more years of good service out of this machine. Then perhaps I’ll be ready for something with Apple silicon…