Getting more bass from Altec Bolero 890c Speakers

I would like to increase the bass response (dig deeper) of my Altec Bolero 890c's speakers. They are rated at 50 watts, and according to the Back-to-Basics Audio by Julian Nathan - simply adding more dampening material would do the trick and would also increase the power handling of the speaker. Is this true? I also read in another thread here, about place a large baffle around loudspeaker, and that Altec did this on many theater models. Has anyone ever tried this with their Boleros with positive results?
They are what they are, Boleros are bookshelf speakers. You're not going to get
deeper bass from them. You can't cheat physics, box size and the woofer's Q
factor are the determining parameters here. Applying random damping materials
will only create other problems like frequency suck out and affect the tonality.
Add a sub if you want deeper bass!

Put them in a corner with spike feet and 10 pounds of sand on top. It will add bass but may not sound better?
I agree with Dkarmeli. You can improve the sound of your Boleros by moving the drivers into new (larger) cabinets and rebuilding or replacing the xovers. But at that point they will be something different and not Bolero speakers.