I think I see something that looks like what you're talking about at 13:55 in this video: 2019 Union Pacific Big Boy 4014 The Great Race to Ogden Fifth Day Compilation
], but it's on the fireman's side. At 16:16, you can see the similar one on the engineer's side.
Here's the Google search for [4014 lubricator]: [www.google.com
In this pre-departure from OERM vid, Ed Dickens describes the four lubricators on 4014: [www.youtube.com
Check out the still photo of the left-side area in question on this page: [4dpnr.com