OK I don’t know if the jacks count as resin or plastic as far as chemicals go but either way you will want something mild.
When I got my first retribution jack I put the empty sprue piece (the one the heads and hand come on if your familiar with the kit) in some simple green for over a month just to test it. The plastic was very slightly discolored but felt perfectly firm and intact.
Depending on where you are in the world you may not be able to get simple green -I believe it is distributed only in North America- but there is likely a substitute. Try researching what works safely on plastic models or whats been effective for people stripping forgeworld models and you will probably be fine. It is unlikely that anything mild enough to strip styrene or resin will be harsh enough to damage whatever plastic PP uses. There is a lot more information on stripping gw models since they have been in production so much longer with a much wider distribution so you would do well to try the gw sections or modeling /conversion section of the forums if you are uncertain what to use in your part of the world.