I've got the rear beam off and can get the tramp on completely by pulling the transoms together a little. But then I can't separate the transoms enough to get the rear beam back on! Annoying.
What I do is; attach tramp to front beam, start both sides in the tracks, put two double purchase lines from the tramp to the back beam [one on each side] and then pull the tramp back a little at a time on both sides evenly. If double purchase isn't enough, go tripple etc. Make sure you lube the tracks with silicone first.
It takes a little while to get it done so be patient.
B.
