Many countries have had to prune their police forces of extremists. East Germany, Northern Ireland, South Africa... Generally, the negative consequences of this have been minor and manageable; it's a path already well-trodden.

Germany in 2019: https://m.dw.com/en/neo-nazi-scandal-hits-german-elite-milit...

That's absolutely a real and serious issue, but it's a separate issue to the dissolution and reform of the East German police during unification, which didn't lead to a communist insurgency.

I completely agree, 2 separate issues, one was successfully finished, as there are no new Stasi members joining the police ranks - but the other issue is ever present. I think there should be "radicalization" checks for any people in position of power (Police/Military), and if they don't uphold the values of the country anymore, they should be let go from their jobs.

Even if that's what would happen (and I don't think it is), an insurgency is better than those people being authorized agents of the state. Better of two bad alternatives, but deradicalization of in-power authorities while they still hold power is an impossibly tall order.