I looked my 660 over this morning and my seat release is metal, so might not be the same. I think if you take a large screwdriver and try to catch the broken end of the broken latch under the center of the seat from the front and pry it up while lifting the seat it might work.
The other thing that should do the trick is if you look under the seat from the front, there are two nuts attached to the bottom of the seat one on each side of the latch. If you have a Sawzall, Cut the nuts off right at the set and that will release the seat. you can replace that hardware later. I suspect the seat latches are available on ebay. Hope this helps, If anything doesn't help ask again.

 

Maybe with an open-end wrench you can remove the nuts. Try that first.

 

Thank you! For whatever reason I can't access the bolts, so it may be hacksaw time!

 

Can you remove the other seat so you can see exactly where they are, and what it all looks like? If not, I can take a photo and then you can see how it is built. Looking under the seat is not easy to see them, but they are only a couple of inches in. Maybe a mirror and flashlight if your other seat is damages as well. I'd try an open-end wrench in about 10-12 MM (around 1/2") My machine isn't here so I can't tell you the exact size at the moment. Don't give up, this is doable. Let me know if a photo will help.

 

I just googled rhino seat latch, and it looks like there is a slight variation in them that may be your problem. Look at the photos of the latches from the bottom and you will see the bolts. In some of them the bolts are recessed a bit. This may make it hard to get the wrench on the bolts. really can't tell how deep they are. Mine are not recessed and would be very easy to get at. One thing, if the part is plastic, it should be easy to break it apart and just get a new one.

 

I pulled the passenger seat today and was able to check the oil and add a bit. I bought a small pump on eBay that screws to the top of the oil bottles and the hose fits in the hole for the dip stick on passenger side. To drain the engine, it's the largest hole in the belly pan under the engine. A 17MM socket will remove the plug. If you can remove the passenger seat you can change the oil, just not the filter.

 

Thank you!!!!

 

so- what worked for you?