Reattaching the speedometer cable & retainer
This is one of the known problem areas on the EX250. It may not happen to you, but it does come up from time to time on the board. Here's what to do:
If your speedo cable comes loose from the instrument console, all you have to do is put it back in. This involves lining it up with the connector mounted on the console and sliding up the little metal connector that is usually hanging on the cable at that point. Then, just turn the loose connector until it locks onto the thread over the console connector, and secure the cable to the console by turning the little barrel connector until it is tight.
You should use one drop of Loctite 242 (blue) on the internal thread of the nut. This will hold it permanently. But DO NOT get 242 down into the cable itself. One drop only.
It's a lot easier to do this if you stand on the left side of the bike and turn the bars as far as possible to the right. This opens up the most room, so you can get your hand up in there. Anyone who has done this before knows it can be a bit of a pain to get the threads lined up right so they bite. This method is the easiest on your hand.
Fixing the cable retainer
If you find that your speedometer cable keeper/retainer pops in and out of the hole easily on the fender, there is a pretty simple fix.
You will notice that the end of the peg is split. The next time you have the front wheel off, find a short, fat wood or sheet metal screw. Use a wide, round-headed small screw, and make sure it's short enough that it won't come anywhere near your tire. Put the peg through the fender, then gently insert the screw into the split peg end. This spreads the peg enough to hold it in place.
You can try to put the screw in before putting the bracket in the fender. This would avoid having to remove the wheel. All the screw does is make the thingamabobby bigger, which is needed because the cheap POS wears away at the edges over time+vibration. But when you make it bigger, you make it stiffer (because you're using more of the meaty plastic) and since it fits the hole a little tighter, there is less vibration to erode the edge plastic.
Wes: I did mine years ago, and I haven't had to redo it yet. If I have to do it again, I'll blow five or ten bucks on a new bracket.