Does it have those oddball speaker plugs on top of the output transformers? If they get stuck in the wrong way, the contacts can loosen and weird stuff can happen.

Is your Leak still running on the original power supply caps?

You are correct. One trick I use is to plug the port(s) on vented speakers to force them to roll off a bit, and that will alleviate some of the burden.

The MX110Z is definitely to be avoided.

If you spent $20 per driver on ten drivers, you’d be in for $200 per speaker in just drivers. The crossover will also be very large and expensive.

You’ll get vastly better results from a $100 woofer and $100 tweeter with a simpler crossover and a smaller box.