1968 Barracuda Rallye Dash gauge lenses removal

exactly. abs cement is mostly abs combined with chemical solvents that melt it. using solvents like acetone some people call chemical welding because the process is joining the original materials. the hot iron provides a lot more control than a thin liquid, especially on disassembly its got to be the first choice.

edit - ps I have not done this 10 times. just agree with Andrews's explanation.
If I had to do my instrument panel over, I would have removed the lenses myself rather than let the plastic chroming company do it. As it was I had to go in and do some touch up using the thick ABS cement.
Also I've made a fair share of plastic repairs on my '85 AMC Grand? Wagoneer and the JB Weld 2 part bonding for the most part did not hold up under the stresses. Permatex was better but for the ABS components - disolving or using ABS cement for bonding has been the best. I have not (yet) experimented with heat but OMM's suggestion will be a part of that when I do.