Might pay to take a nice photo of the subject lens and post if you can Steve, just to see !
Normally minor marks & dust wont effect your viewing much, and Rule of Thumb has it, the fewer times you clean your optics - the better ! I have a couple of small (2x 8" & a 10") newt reflectors and havent cleaned their mirrors as yet, one is a little dusty tho doesN't need attension yet & its 4yrs in my possession
Attached Pics are of my old C8.
1st ) shows the Front corrector lens, thats with the small orange cover circle in the middle of it.
2nd ) Shows the main mirror at the back of the scope, the mirror in these scopes seldom get dirty as they are well sealed from the elements