I have chance to buy a used 17.5" Coulter Dob. (blue tube) from a local guy. He want it for 800-900 bucks (nothing been upgrade), I owned couple SCTs but no nothing about Dob. telescope, but believed it good for deep-sky object.
I need some advides about:
1- What to look for, and how (without test equip.) to inspect (mirror, focuser,..)the scope when I buy it used (not much detail from buying telsc. fqa).
2- For now I will used to observe, but maybe I'll convert it to the truss tube instead a sonotube (or maybe motor control upgrade) next year. Is it good or dumb idea? (of course I'll learn to convert from your folks, books or maybe from John Dobson next month in SF)
3- Is the price above reasonable for 3 yrs old 17.5" Coulter Dob.?
Any advise and pointer are welcome. Thanks
Thinh