What do you mean with "stuck"? It can be possible that the VTF of the suction Arm is too high, in combination with the sucking force that Arm can skip (or stuck?). The solution here is simple, adjust the Arm to zero VTF.
When it is an internal problem with the Arm mechanism I think, best is to contact Loricraft, probably it needs a repair or they can give you some help via Phone.
When it is an internal problem with the Arm mechanism I think, best is to contact Loricraft, probably it needs a repair or they can give you some help via Phone.