lead paint

I've got a front door that's covered in lead based paint. There were multiple layers. I used Peelaway 1 but there is quite a bit of residue left and bits where the last layer of paint hasn't shifted. I've attached some before and after pics. What next? Should I add another layer of the stuff...

Image of partially stripped step below. I'm very new to DIY so apologies in advance for any silly questions. I am using a heatgun (350c) and ffp3 cheap mask (£5). I plan on painting over once stripped. The step (for example central section back) has very tricky to strip small parts of paint, ...