JG Mp5 fire selector/safety not staying set.

[Baz]

For some reason the selection switch on my mp5 doesn't feel like its clicking into place securely. It'll occasionally shift from semi to full when usung it and when the safety is engaged you can with a little effort pull the trigger back. It won't fire like this but thought it might be a connected issue.
I've checked the little spring and nub in the selector are present and undamaged. Could it be the selector plate? Or the spring on the plate?