On Friday, November 29, 2013 9:44:29 PM UTC-5, wrote:

The gas springs appear to be fully extended when the top is open.

When the trailer is fully open, how close to vertical are the struts? (Use a level or plumb bob to define the vertical.) Are they tilted to the rear or front of the trailer?

Does the strut bend at the junction of the rod and the tube? Assuming that it is the rod that bends, does it bend at the very end of the rod where it enters the tube and is the rod fully extended?

Did the first pair of struts fail by buckling? If they did fail by buckling, how many times (approximate) did you open and close the trailer before they failed? (I'm wondering if the trailer ever worked properly or if it was always on the edge of failure.)

When the struts fail, do they both fail at the same time? If not, is the first failure always on the same side? When you say four struts failed, do you mean four pair (eight struts) or two pair?

I only see three possibilities:

1)the trailer always had a latent problem with geometry or strut selection.

2)the trailer developed a problem with geometry or misalignment.

3)The new struts are defective (even though they have the same Part Number, they may be manufactured differently and have different properties. Have you talked to the supplier or manufacturer of the struts?