Spring for Mobius

A small spring with a large responsibility

The spring returns the needle forward into the nozzle at the moment the modeler releases the trigger. Whether a stroke of paint ends exactly where it should therefore depends on its state. A weak or permanently compressed spring is recognized at once: after the finger is released the paint still leaves for a moment, the edges of the spray run together and the shading loses its sharpness. In the opposite case, where the spring is deformed to one side, the trigger offers an uneven resistance and sensitive dosing is practically impossible.

What ruins a spring

The commonest cause tends to be a long soak of the whole rear assembly in an aggressive cleaner. The wire loses its springiness, a dull corrosion appears on the surface and the threads seize. The second cause is mechanical overloading, which occurs when the rear case is tightened by force and the spring is compressed more than it will stand. The third cause is time, because after thousands of presses the wire carries a permanent deformation. It can be told by eye as well: an undamaged spring straightens itself into a regular cylinder once taken out.

Before you replace the spring

Check that the problem really lies here. Dried paint on the needle or a damaged seal behind the nozzle can cause similar symptoms, and that is dealt with entirely differently. Insert a new spring dry and free of grease from the fingers, because a print on the wire binds pigment to itself. The premium bodies have their parts listed for each variant separately, so compare the designation of the machine when ordering. It pays to buy small springs one extra at a time for the store, because while taking things apart they fly off before you manage to register in which direction.