[78-L] cleaning 78s?

[Darren j Ray]

Hello, 

Unfortunately, I had stored my parents' 78s in plastic outers for many
years, and the plastic has leached onto the records. 

I have tried cleaning the 78s using both the Disc Doctor Miracle Record
Cleaner and the Spin Clean. 

https://www.youtube.com/watch?v=u8ZWY46mDTs

https://www.youtube.com/watch?v=DaUKsA_yytA

I've had minimal results. 

Any ideas on how to clean them further?

Thanking you, 
Darren