Have a look at the crossover and replace the components with better versions(caps/inductors). Rewire with point to point wiring rather than those terrible tags they used. The less connections the better.
You will get much better bass and cleaner clearer sound. If you do it well you will be surprised what it is capable of.
Before doing any of the above make sure the diaphram is ok. The glue suffers in UV light and loses its strength which leads to buzzing.
