Thanks for this comparison and the solutions, it may benefit others out here that have these meters.
I would concur with you that the little differences between the old and the new meter you're describing are indeed the result of revision changes. Changes to fix oversights.
The bigger issues, mainly the mechanical misfits, seem to me to be more like the result of changing suppliers.
I've been working on a metrology grade instrument for over 10 years now, and at first we assembled everything in house. By now most modules have been outsourced to a plant the company I work for owns in Eastern Europe. They have very good quality control but when they had just started making them I saw all the little things we did wrong at first reoccur, until they learned about them too.
Hopefully, with your Extech it's a similar thing and they get QC in place again, or otherwise it doesn't bode well for them.
I have an EX830 that I posted a
teardown of only yesterday. Based on what I found I had already decided that the chance of me buying another Extech was rather slim, and your thread reinforced that feeling.
One thing that also plays a role is the price. This meter cost me € 160 in 2007. It's still available now, but today they want about € 250 for it...
Perhaps at the time the brand was new over here and they were selling it under the market value to get a foothold.