From the TFWiki link in the first post...

JP Black Zarak (1988) - the gold feet and shield.

Pretender Bristleback (1989) - gold parts can break when inserting Monstructor's fist.

Pretender Slog (1989) - gold parts can break when inserting Birdbrain in combined mode.

Pretender Roadblock (1989) - gold robot parts where the post-holes are, can break when inserting weapons.

Euro Skyquake (1992) - light-bronze plastic, rear-mounted sight is prone to breaking.

Gen2 Electro (1994) - gold plastic limb joints, like the knees, can break when transforming toy.

Beast Wars Grimlock (1997) - post-holes inside robot legs and hip ball-socket joints can both break.

JP Beast Wars Randy (1999) - spring-loaded gimmick could strain the brittle plastic enough to break it.

Beast Wars Magnaboss Silverbolt (1997) - gold tail section can break.