You could in the future,fill the idler holes,and clean off the idler mount.Then
Drill an off center hole in the idler,so you can rotate it to the front,like an eccentric.Then on the mount,use a metal rod.
Me,I buy after market,just because of this possible problem.All my Italeri suspension based vehicles get the idler mounted,squeezed with a clothespin,for a day or more,before any other work goes on...