I found that the best way to arm it is to click on it with the mouse, and by draging it down, the spoiler lever moves to 100%, then dragging it up, it moves the lever to the ARMED possition. There is no spoiler lever animation, so unless you turn on the Tooltips (as seen in the attached image) you won't know it's armed, or what percentage they're set to. It's annoying to have to use the Tooltips, but at least it helps.


To turn on the Tooltips:
General Options > Accessability > Under User Interface:
Instrument Name Tooltips: Instant
Instrument Description Tooltips: Instant


In the attached image, I have the Minimum Text Size set to 18, and the Interface Scale set to 70 because if I use 100, the Tooltips are huge. Using less than 70 is too small for me to see well seeing as my eyes aren't as good as they were 20 years ago.

I'm pretty sure I understood your original post.
Because there is no animation of the Spoiler (airbrake) Lever, all I was showing you was how to use the Tooltips to see
1. If the spoilers are armed
2. What percentage of the spoilers is being used to slow the aircraft