So, I just did this. 10 minute job, and no problem with tension at all.
My new arm turned partially white at the bend. I think happened when I was pulling up on it to get the bottom bolt in place (it was just a little low). I loosened the wheel lock but I was afraid to release it entirely. I needed to loosen it for another reason - since I'd opened the awning with the arm bent, the lock was holding the arm in an awkward position, and it didn't want to go back to vertical without loosening. There didn't seem to be any tension in the arm even with the lock loosened.
If I were doing it again, I'd put the top bolt in first, not the bottom, then get a helper to pull up on the main tube while inserting the lower bolt, instead of doing it alone. Or I'd confirm whether it's safe to release the wheel lock, which is probably what I was fighting against.
I tried to straighten the old arm, but what I found was that it tended to twist, so simply stepping on it, for example, wasn't going to do the job. I was able to work around that with clamps, but I just didn't have enough clamps to make it happen, so I gave up before I hurt myself, the house, the car, a bicycle, etc. - I could just visualize a piece of aluminum flying across the garage.
1995 Airstream Classic 30' Excella 1000
2014 Ram 2500 Crew Cab with Cummins 6.7L Diesel
Sold but not forgotten: 1991 Airstream B190
Sold: 2006 F-250 6.0L Powerstroke Supercab