Triumph Repair: Doesnt shift into first and second, spitfire 1500, hub assembly

Question
QUESTION: I reinstalled the gearbox in my 1980 Spitfire 1500, and when I try the gears (wheels off the ground), it won't shift all the way into first or second. It goes part of the way, and even turns the wheels. It shifts solidly into third and fourth and reverse. What did I screw up this time?

ANSWER: Hi Tom,
You need to remove the top cover and slid the hub assembly with a pry bar so as to engage each gear to see if the problem is in the gearbox or in the shift tower. You should be able to easily pry each hub assembly into gear. Don't try to drive the car that way because even though 1/2 and 3/4 hubs snap into place so you can feel and see them engage the reverse arm does not and with out the cover reverse car shake or vibrate into gear and if any two gears are engaged it locks up the gearbox. So to test each one of the gears jack the rear up and use the rear wheel to try to turn each gear as you test each one.
I always manually click each hub assembly into gear before assembling the shift fork assembly in place. Note that you don't have too much end float in the 1/2 assembly on the mainshaft. This would make the shift fork run out of travel trying to shift it into either 1st or 2nd gear.
Let me know,
Howard

---------- FOLLOW-UP ----------

QUESTION: I hadn't thought to manually pry the 1/2 hubs into gear with the cover off. That's a great idea, and I'll try it. I didn't know the shift tower could be the problem either. The car's front wheels are on ramps, and the rear is up on jack stands--that's the state it was in when I was testing the shifting. And another thing: I have another gearbox I can reassemble in case I can't figure this thing out. But one of the small teeth on the input shaft is broken off. Since the synchros are guided onto the gear by the synchro rings, can I do without that one tooth? I don't think that input shaft is available any longer.

Answer
If you are talking about on tooth of the spline that the syncro and sliding hub go onto, it will not matter if the rest of the spline is ok but if the tooth is bent over or a piece is stopping the hub from sliding over it then that can prevent the gear from engaging. But the 1st motion shaft is 4th gear not 1st or 2nd gear. 1/2 are at the back of the trans.
The manual prying will tell the reason, don't forget to check for excess end play of any of the gears.
Howard