Follow-Up:
Winnebago is right on this one. Although your parents may be in their 70's and might not be spry enough to climb up on the roof and look around, they should have read their owners manual to see that it clearly states in there that they do need to check the all the external seams and seals every six months. If they can't do it themselves, then they need to take it to a RV dealership every six months. This is routine maintenance on a motorhome, something that is required on all vehicles (routine maintenance). It is like saying your paint on your automobile is really bad and rusting in some places when you've never washed or waxed the vehicle. These vehicles don't maintain themselves, just like cars don't and just like houses don't! There may have been something wrong with the tone of Winnebago person when they were talking to you, but what they actually said is completely correct and well-known in the RV industry and should be known by all RV owners........if they would just read their owners manual. Sorry!