2000 Silhouette Trasmission

Hi there! My 2000 Olsmobile, all of a sudden, stopped shifting into overdrive. 2nd and 3rd shift is just like when new. OD shift just stopped happening. When in 3rd gear, at higher RPMs, if I take my foot off gas the car seems to shift into Neutral (RPMs drop down to idle speed), until I hit the gas again, but it stays in 3rd gear.

Shops are saying "need a rebuild for $2,200.00", but I'm hoping it's something less drastic. I've checked the fluid levels and run some Slick50 through it.

Any ideas?

Thanks

Paul
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