Jack,

Where in Virginia are you located? We always interested in having more classic Mini owners as a part of Mid-Atlantic Minis.

Email me direct if you'd prefer.

Jemal, and everyone,
Thanks for all your suggestions.  This all makes sense, once it is explained.  It would have been very helpful if someone at MM had given me this information up front.  I would have been much more comfortable with the car and the "new" gearbox, knowing this.  Once I had that advice that I referred to in September, from someone at MM, I was able to relax and drive and enjoy the car again.

Perhaps an information sheet would be a good thing to include with newly rebuilt gearboxes, in future.

Thanks to all, and to all Happy Holidays!
Jack in Virginia

It's not intuitive that it can be ANY slightly tight synchro ring in the box that causes difficulty shifting into first. That gear puts a drag on the mainshaft, making the trans feel like a 3-synchro - except that you can't just crunch it in! First gear is seldom replaced. Indeed they are so strong that only the most determined abuse in a previous life renders them unusable.

It's absolutely true that most rebuilt gearboxes will work better with some patience over the first few hundred miles. And learn a few tricks like grabbing a gear that goes in easy to stop the mainshaft (when at a standstill of course - it's a moot point when the wheels are turning), and then slip into first without releasing the clutch.

It could also be the "newfuzz" on the new clutch disk causing a bit of drag, or any number of clutch related items. Got a slightly worn pin or haven't kept a close eye on your clutch adjustment as you work off the "newness"? And you won't believe how many times it's those nice new floormatts keeping the cluch pedal from it's last eighth inch of travel that turns out to be the culprit!

I myself carefully fit the new synchros looking for the best fit to all the gears. And I bring the car to Mini Mania's big parking lot on the weekend and back up a few laps. If all else is good, that's the BEST way to help the parts get to know each other, as the mainshaft turns all the synchros backwards through the all the gears in constant mesh with the engine. Simple, right?

What Mike said.

always go to 2nd before 1st at a traffic stop.  It should then slip right in.

Good to know you are finally seeing results.

Good afternoon,
    In case anyone else installs a MM rebuilt gearbox and is worried about unwillingness to go into 1st: over a year ago I asked MM and this forum why my "new" gearbox would not willingly shift into 1st.  It was built and installed in late 2018 and I was not enjoying the stress of trying to drive it in local small town traffic with this issue.  MM tech guys told me to drive it in reverse as much as possible, but it's difficult to get many miles in reverse!  Not to mention, repeating that advise got me a lot of funny replies!
    Last December I asked the MM help desk about this and got this very encouraging reply: "If this is a fresh rebuilt - this may be most of the problem. When we rebuild gearboxes here, we ALWAYS replace the 1st gear and synchros as they are especially prone to wear and failure - this means these brand new parts will require time to "get to know each other" and we suggest a break in period of 500-800 miles. Clutch adjustment is important and a common problem as well."
I have been patient and tried all the advice.  Also changed to Miller Classic Mini Oil.  Now, at about 400 miles since rebuild I am seeing improvement.  It still does not go into 1st in motion but that is not a serious issue.  I can easily go from 2nd into 1st with no problem.
So, progress!  I don't put enough miles on it but with many years to go I will.  You guys who do drive your car a lot will no doubt get past this quickly.  So I would say buying the rebuilt gearbox from MM turns out to have been a good decision and certainly at a reasonable price.
Best regards to all,
Jack