white spaces on printout

Difficult to visualise the problem from your description, but regular blotches on the printout can be caused by toner being burnt onto the (HOT) fuser drum.

If you can take the printer apart, there will be a roller in there somewhere (like a rolling pin). If you can get at it, have a look to see if it has got a black carbon deposit on it.

This can be scraped off with the blunt end of a wooden pencil, or a wooden spatula. DONT use a screwdriver, or you will ruin the fuser.

Be very delicate when scraping, as any damage to the fuser will cause further degradation to the printouts.

If only part of the roller is visible, you will need to scrape a bit, turn the cogs, and scrape a bit, until clean.

Hope that helps, failing that, you might need a new fuser unit..