chmod,
I am sorry for my slow response. I am flying this week, so my time at the keyboard is limited.
I thought about wrapping electrical tape around the port to close the gap but I'm not sure if this would be ok acoustically. Is there some other way to make the port fit more tightly into the hole?
I think you are on the right track. I think the tape will work fine. However, I'd put the tape on the hole, rather than the tube. To get a nice seal, use poster-putty for a temporary "glue". When you are satisfied with the port tuning you can use some model glue, or Liquid Nails Green label for more solid adhesion. I must admit using poster putty on my personal speaker's port tubes for... about 3 years.
I also made the woofer hole 4.5" away from the edge instead of 4.25" by accident. I hope that's not a problem.
This is measurable, but not audible. It's no problem.
And the woofer recess on one side is a little tight such that the driver needs to be pressed into its hole.
... been there done that. The solution is fairly easy. You will file some of the flange from the W18 driver and finish the raw metal with black finger nail polish. The BASE of the W18 driver flange is slightly wider than the FACE of the W18 driver flange. The flange edge is slightly tapered. You will want to file the wider base of the flange slightly for a good fit. I have done this 3-4 times, and it's not visible after the driver is mounted. The most difficult part is mentally getting past the thought of using a file on the edge of your W18 driver frame.
The only caution I will offer is that you have a vacuum cleaner very close to you work area. You must ensure the metal filings do NOT get into the motor assembly. A vacuum cleaner easily solves this problem.
It appears you are making very good progress
Dave
