I would go in on the suggested route and take a machine along and see how it goes, get some idea of the machine and it's capabilities
They are a difficult machine that has a narrow market.
My experience is that if you can market as a non invasive service there is an opportunity. Internal chewing gum removal to store entrances, hospitals, supermarket entrances, shopping centres, places you can't use a wet chewing gum removal service.
Mine have been used inside the entrances to a hospital and plenty of supermarket entrances.
You can literally clean next to someones foot with no worry of repercussions.
Pricing - there is the golden question.
Chewing gum stops being litter when it is flattened and the problem is ignored by the vast majority of local authorities. Never really marketed the services, though I have 20 000 leaflets for both up at my unit.
I did a storefront in Bath on Wednesday night, I just used the pressure washer and blew the gum off as I went along, It wouldn't be worth my while removing the gum with the dry steam machine and then pressure washing,
If I get a bad pressure washing job I add a chewing gum removal price onto the clean and do it that way, some of my works are on day/night rates - subcontract work, on my own work I price everything.
Graffiti is chems, as hot as possible for speed - rinse off, tidy up and get the invoice in. By the time your machine has heated up someone else may be onto another job.
Probably not the best person to ask on pricing because the refurb programmes aren't open for everyone to price up and work, mostly on rates and multiple services on one location so no mass competition and a graffiti tag may just be picked up when cleaning a perimeter area, which may be walling, walkway, railings and other immediate parts.
When I need to take one of my machines I charge more. When i use chemicals for graffiti I charge more.
You have a reasonably niche machine, find a sales avenue, turn that opportunity into a job and repeat is the best I can offer.
I may pull my finger out with this service after this.
I already have a couple of ideas