As long as you aren’t applying a lot of pressure to the drivers while you are “feeling the vibration” it should be fine.

The drivers have to be sturdy to move the air needed for the vibrations to be felt, but do not accidentally push your hand through them, or have any kids copy you!  An easy way to see if the Sub is working is to cover the open port with one hand.

Thank you! I probably check it gently with my fingers every couple months (while dusting it) to make sure it’s working well.

There is an easier way! Toggle the Sub on/off via the app when a bass heavy track is playing and the difference is obvious if the Sub is working.

Personally I wouldn’t do this. Grease could build up and won’t do the cone/suspension a lot of good. Put on a track with a bit of bass and use a torch. 

Or as we call them here in the US, a flashlight. ;)

Ah yes. “Torch” is perhaps too readily associated with “pitchfork”...

Indeed, the first thing that came to my mind was burning witches ;)