Ideal Mold

[Walks]

If you're going ask about mold to handle fit/interchangability then you need to specify if the mold is an old style small block single cavity. Or a double cavity. The old small block took one size handle and the double cavity another.
They are referred to as small or large handles. The THOMPSON CENTER mold handles will also fit the small block LYMAN/IDEAL molds.
Today LYMAN no longer makes small block molds or handles to fit them.
They now refer to the 2 sizes of handles they make as LARGE & FOUR CAVITY.
LYMAN switched names stamped on their molds from IDEAL to LYMAN in the early to mid 1950's.
LEE handles do not always fit every small block LYMAN mold.
I think LYMAN made small block&handles into the late 1970's or even later.

[Alcast]

I don't think the OP specified whether the brake cleaner was "non-chlorinated" or not. He just said "brake cleaner". I just play it safe and stay away from brake cleaner, period.

I didn't know that.Thanks,I'll stop using it.This forum is great;you always learn...even at my age!

[avogunner]

......Ideal molds hold a certain allure of days gone by, they haven't been made for many decades. I've found Ideal molds function better than their newer Lyman counter-parts. I am always on the lookout for inexpensive Ideal molds .....

Same with me and as my collection grows, I have more appreciation for the artisans that made them. I concur with Jon's cleaning methods also. Your patience will be rewarded.
Semper Fi