Moving coil carts should be cleaned quite often. I find that after about 2 weeks or about 20 hours of play, enough debris accumulates on the cantilever that it begins to deaden the sound a bit.
I use a 50/50 mix of distilled water and isopropyl alcohol to gently brush the stylus. MC cantilevers and output are so delicate that you’ll notice an improvement.
Also, you’ll be better able to see what’s going on with a clean stylus.