Sometimes Rikaisama just stops functioning. It is still there but hovering over a Japanese word doesn’t invoke the usual pop-up box.
Turning Rikaisama off and on again doesn’t help. When it restarts you get the Rikai startup message, but when you hover over a word, still nothing happens. The only way to fix it seems to be quit and re-start Firefox, which is pretty annoying.
Fortunately I have found that in almost all cases the cause is quite simple and can be solved easily without re-starting Firefox. There may be other cases but nearly all the time this works for me.
What has happened is that Rikaisama has gone into Super Sticky mode (probably because one inadvertently pressed the shortcut key while hovering). In this mode boxes don’t go away after you move the cursor, but they also don’t appear on normal hover. You have to ctrl-click or alt-click in order to get the pop-up.
So the answer is simple. Ctrl-click or alt-click to get the normal box, and while the box is displayed, press the Super-sticky shortcut key (U by default) to toggle back to normal mode.
A simple fix for a rather annoying Rikaisama problem!