Transmission problems

[Baja GN]

Recently I had the engine rebuild for the 2nd time. When I was testing it as if launching at the track, after the 2nd launch, the tranny began acting strange. Before this, it was working fine. It would not get out of 1st unless I punched it hard and then it would shift, but it was shifting into 3rd. 4th, sometimes it would come in and some time it would not. A trans shop told me that the band for 2nd was either damage or broken. Since the tranny had to be taken apart for the band, I decided to rebuild it (last rebuild on tranny had been over 10 yrs). A couple of days ago a friend finish rebuilding it. He suggested to get the Raybestos Pro Series kit for the rebuild. The problem now is that it will not go into 2nd. 1st, 3rd & 4th are o.k. The previous rebuild, a shift kit was put in it, but I don't know which one. My friend was careful in taking it apart and put it together the same way it was. We are at a loss as to what the problem is. Since I was not with my friend when he did it, I have to believe what he is telling me. I would appreciate any inputs as to the possible cause of the problem.