Thanks for replying.
Just to clarify one thing, the front cabinets (above the windshield) are not a problem. Its the cabinet above the passenger seat that doesn't open fully.
I'm sure the previous owner did not modify the frame (this thing is made out of steel and very heavy-duty). Previous owner did install a bigger TV but it still fits within the frame work. Either Beaver messed up when they built the coach or perhaps the cabinets over the passenger seat where made too tall. Maybe there are two different sized cabinets depending on whether or not you have the motorized TV mount, and they got the wrong ones installed at build time.
Now that I think and write about this, I can't see anyway that a previous owner could have done anything.