2016 Soft-close tailgate slamming open (not damper)

Started to notice my soft-close (or is it soft-open?) tailgate slamming. I looked through these threads and everyone with this issue replaces the damper bushing. The bushing does not look broken on my truck. However, I did notice a sticky syrup like substance on the floor under the passenger side bumper. It looks like the "other" part of this system has failed. Has anyone encountered this or know what part number it might be?

 

Item 12:

https://toyotaparts.lagrangetoyota.com/v-2017-toyota-tacoma--trd-pro--3-5l-v6-gas/body--tail-gate

Better photos:

https://www.ebay.com/itm/233631095876?chn=ps

 

Cant help myself. Hahahahh. Im 12.

 

Thank you! I've been looking for this for months!

Has anyone replaced? Can I access just by taking off the tailgate or do I need to remove the bumper or tail-light housing?