Make sure you let the medication sit out of the fridge for about 20 minutes before you start infusing, otherwise it will take FOREVER to run through. Personally, I hate the eclipse pumps for that very reason. I can never tell how long it's going to run. I miss the days of having a pump with an alarm on it to tell me when the infusion was complete.
Also, make sure you don't let your line go completely dry. The vacuum pressure that occurs if you let the thing run completely to empty will make it VERY difficult to unscrew the line when you're done.
Hope you're feeling better soon and that Merrem does the trick for you.