bialko.....have same machine '01 rxdi, had same problem...here's what I suggest.
4k for a new motor on what an authorized sea-doo dealer told me "the 951 motor is the reason I have a job". for about 5k you should be able to get an 05 rxp or rxt with 215 hp very reliable 4-stroke motor. with the parts on your '03, I'd go to greenhulk.net and say you are just parting out you're machine and should be able to sell the parts in a month or two.
As far as SBT goes, don't waste your $$. I've had 2 buddies buy thier motors, even paid more for the extra warrenty and still blew those motors up, SBT slaps parts together using the cheapest components they can find which are subpar when compared to a factory built motor.
I know SBT has your motor for about 3k but trust me, in the end you'll be more than happy with upgrading. kinda sucks to do it in the middle of the summer but when I brought mine in to get the rebuilt motor from seadoo (1st time), that motor was on backorder because so many had blown and it took me 4 months to get my craft back anyways, we'll I did get it back by Oct 15th, just in time to put it in storage, boy was I upset.
Sell your parts save your $$ and come Sept/Oct, you should be able to pick one up for a very good price. I've even seen some '06 RXP's for $4000, but you gotta be willing to move fast sea-doo's with those prices just don't last long. the 215HP 4-tec motor (4stroke) is a great motor and if you throw an impeller on it you can see 68-70 MPH, I know you can't go that fast on the RXDI. been there done that, upgrade, you'll love the new machine!