My experience with a decontacted etalon was that the solar disk will come to focus with a sharp limb but won't show any detail at all. If the etalon is decontacted it's likely (but not certain) there are loose parts inside. If there are, you can hold the etalon in a very quiet place and slowly rotate it and listening closely you may be able to hear the parts moving inside.
If you hear parts rattling around, the etalon is finished.
As EVS points out, components in the Coronado blocking filters are prone to deterioration of the coatings and/or substrates. The old timers believe this is the result of thermal cycling and/or moisture. Many users use desiccant packets to control moisture and depending on the heat load the blocking filter is seeing, some people add an ERF of some type but your scope should function as designed without it.
The etalon and the ITF are the two components that commonly fail in H-alpha scopes. Some of the Coronado scopes had the ITF built into the objective.
On most of the Coronado and Lunt blocking filters, (Lunt uses a blue glass filter) the ITF is the 1st glass component the light hits on the blocking filter diagonal.
Since you don't have other known good components to swap out with, you should familiarize yourself with what a good ITF should look like on your scope. They don't all look the same. The link EVS posted is a good place to begin looking at those components.
(Thanks to bob71741 for pointing out that the ITF is a more complex filter than the blue glass found in Lunt blocking filters)
Edited by briansalomon1, 07 May 2021 - 01:37 PM.