Disassembly of HP-19C

[[kby]]

Generally a larger tip (like chisel) seems to enable faster heat transfer in. However, if it doesn’t work, then you need to approach the problem in another way rather than holding on as long or significantly longer than with a pencil tip.
Be sure you’re not just thinking the solder isn’t melting because the surface still looks intact but it’s melted underneath.-kby[/align]