Drag on driver causing noise

I bought a pair of old bookshelf speakers with the intention of using them as a part of a desktop setup. The seller was straightforward that the cone was rubbing, and it was affecting the sound. The first time he demo-ed it, the distortion occurred as he said; he paused the music, we poked at the driver to feel the drag (which there was), then he started the music back up, and the problem temporarily abated.

I got a discount as a part of my purchase, my question is what are my less invasive options to try before I start taking off the dustcap/cone/etc?

Thanks