[Gelbster]

On the M96 a common Mode of Failure for ticking lifters is the small internal orifice inside the INA lifter plugs up. Then the tappet gets 'hammered' into the bucket so hard it jams in an over-compressed position. Then the ticking begins.
When you dismantle lifters in this condition you need visegrips to extract the tappet from the bucket .Obviouly this renders them unuseable but your curiosity is satisfied. Perhaps I am being unfair to the snake oil vendors, but I don't think any solvent would free the tappet in such circumstances.
In the reported cases of miracle cures, seldom has a careful diagnosis confirmed lifters to be the problem,prior to magic treatment. It may be that the snake oil+lifter cure was actually something else.
That said, where is the harm in trying some Rislone? I did. Hypocrite .It did not work unfortunately. Hopefully the upgraded lifters from INA are better. INA had exactly this problem in the many other engine brands that used this specific(now superseded) part number.

I suspect that the probable cause of the Lifters being "hammered"= the tappet jammed into itself & therefore rock solid+ excessive clearance was from the P.O.
1.Ran engine with low oil pressure
2.&/or used excessively thick oil+/- thickening additives to hide a bearing knock.
Lesson - Respond immediately to a low oil pressure warning
Use the thinnest of the recommended oils - to ensure the tappets in the lifters are reached with life-saving oil as sonn as possible after start up!
Jammed Lifters can Not be fixed Even with Vise grips you can't separate some of them !