Big point is the lens - is it clean?
You can remove the focuser and take it apart - I have just done it to one of mine. I sort of had to as I could figure out how it worked and so make adjustments.
Flocking/blackening the inside of the tube is unknown and you could I suspect manage that.
So the big one is that front lens and the state of it.
If a cemented doublet then could be easy = take cell out clean both sides and replace.
If separated doublet bit more involved and could be best if someone with some experience did it. Mainly it is making sure that what come out goes back in as it came out.
As above maybe wander along to a club and ask.
I would do it myself, but worked as an optical engineer for 5 years so not overly scared about the described scope. I would hesitate if it were a triplet or good ED. Just not so easy to get the lens back to ideal/optimum locations. But at least it would be me doing whatever to my own scope.
Have met people who say "I can do that" then I find they are not sure what a lens even is.
As said check the lens. If just rear and front faces are mucky they can be cleaned easily - spray with a cleaner to soften the crud first. Then lots of tissues and cleaner.
Focuser do that yourself. Not difficult and you will find out how the thing works and adjusts - I do not like mine. Just seems odd.
Inside the tube is likely to be a couple of long handles brushes and eventually some matt black paint.
Before any paint remove the lens cell !!!!