Frame problems

[Montana_1421]

I purchased a 2000 Montana Model 3280 last year. The previous owner did not know about the frame problems. The dealer has been in touch with Keystone for the past 3 months and they will not give him an answer about fixing the frame problem.
How would I know if the repair had been done at the factory other then a serial # check.
Are there visible corrections that would have been made at the factory
What do I look for that would indicate that an after market repair has been made.