Modern markers come with a very detailed manual, loads of PDFs to download/youtube videos to watch, and are usually very easy to tech (I do all my myself).
Timing a cocker, or saving a leaky mag is a much trickier process, hence the popularity of servicing in the past. These days, either drop it in the manaufacturers tech tent at an event, or watch someone hold your hand through it on youtube.
That said, most shops/sites/makers would be able to sort something out if you needed.