Increasing bass on floor standing speakers

I wrote a lot about getting more bass here:

https://speakermakersjourney.blogspot.com/2020/04/how-to-not-buy-subwoofer.html

Thanks everyone... I've got a few things to try. I noticed that the cable used to wire them was pretty thin so I'll fix this up when I check if they are in phase or not. 

Two suggestions:
1. Mount your floorstanders on isoacoustics Gaia feet. 2. Add (REL) subwoofers. 

Upgrade your speaker cables could make a big difference on bass. They did on mine. 

Did they ever sound strong? not any more?

Have you checked to see if the woofer’s cones and/or surrounds are in good shape? Look for pin holes, press in, check cone and surround stiffness: see if ’spring’ action feels good or kind of weak.

I have re-coned my 15" woofers (made in 1958) twice. They sound good, but I will be checking them soon, it’s been years.

I have to remove the back panel, then remove the driver from the front panel, check them out.