Channeltron contamination/cleaning

I have some channeltrons placed in a close-to-UHV environment (~10^-8 torr) where I suspect contamination.
The chamber in which the channeltrons are placed was previously part of an oil contamination accident but has been cleaned. However the channeltrons were placed inside the chamber after the contamination but before it was discovered.

I'm wondering if someone knows

1. how one can know if that is the problem (how does it show on i.e. the signal)

2. if 1, how to clean the channeltron if possible (found something about isopropyl and 150C baking)

When oil contaminated my UHV chamber I replaced my MCPs, and had the phosphor screen cleaned and recoated. For the metal parts I scrubbed with acetone, followed by a methanol rinse. Anything that fit into the ultrasonic cleaner was run with acetone first, then methanol.

Cleaning of the chamber has of course been done since the oil was discovered, and I'm about to test the channeltrons (from Dr Sjuts) in a clean environment but I guess you're right that it's best to consult the manufacturer about the cleaning process of the detectors if they turn out to be contaminated