Removing old conformal coating?

[TERRA Operative]

I have an old bit of HP gear that I am giving a spit polish (5005A Signature Multimeter) and the conformal coating/clear spray coating on the PCB's is looking a bit blegh and could to with a fresh application.
I found when cleaning the boards with isopropyl alcohol that the coating started to go a bit tacky and in some places I could rub it off with a bit of effort.

I'm wondering if there is any product that I could use to dissolve the coating somewhat easily but one that wont damage the silkscreen or components?

Anyone have any suggestions to try?

[Tomorokoshi]

Does that seem to be a clear, hard coating or that soft coating?

I looked in the 5005A manual and I couldn't find the conformal coating listed, so determining what works might require experimentation.

If it's the clear hard coating, then it might be acrylic. I have experience with Humiseal 1B73:
http://www.humiseal.com/products/aerosol-products/1b73/

But I have not used the remover:
http://www.humiseal.com/products/strippers/st-1080/

For my own boards I just use Rustoleum Crystal Clear Enamel. It's also acrylic based:
https://www.rustoleum.com/product-catalog/consumer-brands/stops-rust/clear-enamel

Something similar may be available in Japan. Maybe at places like Doit or Homepic.

[TERRA Operative]

It is a hard clear coating, I think a type of acrylic laquer.
Isopropyl alcohol doesn't really touch it much, (the coating only gets a little tacky) but methanol does, except methanol also takes off the silkscreen too....

Replacement coating is easy enough to find here in Japan, but I just gotta get the old stuff off first....

[tru3533]

Have you tried to find the glass transition temperature?

The glass transition temperature is the temperature range where the polymer substrate changes from a rigid glassy material to a soft (not melted) material.

Heating the board to around 100 degrees celsius works great in many cases. (boiling water)
And then the substrate can be removed easily with a flat bamboo stick or similar.