How can I remove the plastic cap from my idler?

[birb]

Heng Long 1/16 King Tiger

[starcop]

Heng Long 1/16 King Tiger

It might be threaded. I can see the pick tool didn't work. Maybe try twisting with your fingers. You might have to find a building diagram from a similar tank online. You can possibly drill a hole, then use plastic fill and re-paint..

[starcop]

Heng Long 1/16 King Tiger

Heng Long Tiger 1 RC Tank - How To Separate The Upper & Lower Hull - Bing video. Motion RC. Customer service can point you in the right direction.

[UltraVargen]

It's not threaded. You need to get leverage under the plastic rim. Be careful not to damage the plastic.
I use a nylon spudger tool for mine. You can buy these super cheap from places like eBay, Amazon, Aliexpress, local phone-repair shops, etc.

[SoCalBobS]

Heng Long 1/16 King Tiger

For most HL tanks, there is a tiny notch in the hubs. A pry tool, like UV recommended or any pointy object will pop it out. They're not glued, just press fitted.