Track pin press vs sledge hammer

On this machine I bought Someone put all new undercarriage but left the old chains. Hasn't been too long because there is very minimal wear. I found a set of very good tracks from a dismantler. Now one guy told me you have to press the pin back in, and another told me to just heat up the bosses and start hammering.
Any input from you guys would be appreciated and what is a average cost to press pin in?

Thanks

Track pin press vs sledge hammer