My old Thinkpad immediately dropped about 30° C after I replaced the thermal paste. The old paste had apparently gotten too hard to be effective and the laptop had shut down a few times because of the heat. Thankfully, there doesn't seem to be any permanent damage. I confirmed that the fan was working before reassembly.

This is an easy maintenance item. The instructions and the photos are excellent. I used Arctic Silver 5, which appears to be the the same paste that was used by Lenovo.

I ordered a Kastar battery pack from Amazon for $8.99. It comes with two solder tabs welded onto the terminals. I peeled off the welded foil tabs on the orignal battery pack and soldered the ends onto the new battery tabs. No damage to the new battery and it works great. The battery pack: https://www.amazon.com/gp/product/B08CCF...

I ordered a Kastar battery pack from Amazon. It comes assembled, with solder tabs welded onto the terminals. I peeled off the welded foil tabs from the original battery pack and soldered the ends onto the new battery tabs. It works great. The battery pack: https://www.amazon.com/gp/product/B08CCF...