Pentair FNS Plus filter

Chasing issues...

I had DE blowing back into my pool. Pulled the cover off my filter and found a cracked manifold. "Easy fix" I thought. Went to the local pool supply and got a replacement manifold. It looked a little different but the guy said it was a new, improved design. Went home, installed new manifold, put everything together and still had DE blow back. Took apart again and found some damaged grids. Decided to go ahead and replace them all. Put everything back together and still had blowback. I gave up and called local pool service. Technician came out and said I had installed all parts for FNS, not FNS Plus. Said the manifold and ALL grids needed to be replaced at a cost approaching $1K. :mad:

On top of that, on one of my fact finding missions, pool supply store guy told me to change out spider gasket. In the midst of scraping the old super glued spider gasket out, I cracked the sight glass. Pool service company says I have to replace the whole multiport valve since the sight glass is glued in.

So...my questions are:
What is the correct manifold part number for FNS Plus 60? Do I really need to replace the brand new grids too? Is there some type of epoxy that I can put on the crack in the sight glass?

I would REALLY like to keep at least some of my money.