1) Replace internal acoustic stuffing with more material and a higher grade material(ideally 4-8 lb/ft^3 density rockwool board or fiberglass board). If you can't easily get it, I will mail some to you for very low cost(the stuff is CHEAP) if you are in the USA. PM me for details.
2) Fix vibrating metal can magnetic shield on woofer. Use liquid(NOT gel) super glue and squirt some generously around the seam where the can meets the driver - this will stop the vibration.
3) Fix air leak number 1. On the tweeter, where the tweeter motor connects to the tweeter faceplate, there is no seal between them. Use plain silicone sealant and squirt around the seam, being sure to also squirt around the base of the electrical leads.
4) Fix air leak number 2. On the plastic waveguide around the tweeter, there is no seal where the tweeter connects to the waveguide. Remove tweeter from the waveguide (4 screws on the back) and use bluetack, rope caulk or speaker gasket puddy; flatten with your fingers and place small amounts on the ridges of the waveguide where it connects to tweeter. Re-mount tweeter and tighten screws. Scrape off excess putty on the front that squeezes out with fingernail.
While this speaker is super low cost, it has far better linearity and off axis response than most that cost far more money[1]. It has 1.25" MDF front baffle, 0.75" MDF cabinet, MKT film caps, very high power iron core inductors(as opposed to the small ones normally used in low cost speakers that easily saturate at low power levels), cast frame woofer and relatively low distortion even when used at 100dB(assuming an active crossover is used to limit LF, of course).
