Several Generation One toys differ from prototype to final production models; Astrotrain is one such example. Early photos depict this toy having several differences, notably the arms had a telescoping system for transformation that extended the arms. For whatever reason, this feature didn't make it to the final toy. This is where TFW2005.COM member nonmetal comes to the rescue with his custom work! Below, he details how he used arm parts from a G1 Swoop figure to install this much-desired feature back to Astrotrain. He details his work below:

"I love Astrotrain with extendable arms. Below here is a pictorial demonstration of how I assembled Astrotrain's arms with a part from a G1 Swoop's arms so that they could extend. It was not easy, but was well worth the meticulous work and worth the skill-building lesson. The lower arm halves were carefully clued together so that the sliding mechanism would not be ruined. One thing to watch out for is to not glue the ball in the ball joint. To attach at this point, I glued and then filled with two-part epoxy putty for plumbing.

Thanks, check out my Astrotrain [customs] for the complete bot!

http://www.tfw2005.com/boards/radicons-customs/1033931-g1-astrotrain.html
http://www.tfw2005.com/boards/radicons-customs/1034654-g1-astrotrain-part-2-a.html


Here are Astrotrain's arm and Swoop's disassembled arm:

This shows the screws removed and the opened arms:




The nubs inside Astrotrain’s arm for the screw have been grinded down with Dremel. It can be a little sloppy because it is on the inside. Leave the bar so that it will act as a stop for the slide. Here is the test fitting slide mechanism:




This is a close up of grinded out section from above:



There is a notched section on Swoop's arm. You want that, but only a bit of it just to catch. If you leave too much, the arm will not be able to compress all the way:




Cut off top of Astrotrain arm bits. Here is test fitting again:




Here is more test fitting. You can see that a square hole will have to be notched out of the upper piece:




The ball joint was removed first so that it does not get damaged. Very carefully Dremel away hole using a hobby knife to help square it off, while test fitting the parts as you go:




Now, I had to glue in upper arm. The ball joint had to be in place so I had to be VERY careful not to glue ball into socket. I put a little olive oil on the socket just in case and used glue sparingly. I found out the hard way when I messed up the second arm and had to sacrifice another Astrotrain. On this one, I drilled out a tiny bit too much, so I filled with epoxy putty (which happened to be a perfect color match).

On the lower arm, the screw cold no longer hold the arm together, so I had to glue the lips of the halves. Again, I had to be careful about gluing that I did not glue slide into fixed position:




This is the finished arm:"

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