I know some may balk, and I admit myself I didn't get really deep on the DP-30L I bought for my Mom to enjoy. (I bought for $100 from ebay, like new condition, and I sold it for $100 after my Mother's passing)
But I did at least dial in the Arm, and simply checked the alignment with a simple Mofi Geodisc I had.
Still, Table set up with this one is really no different than if it's a $10,000.00 Turntable. Same checks-tests needed-applied if you wish to get the best from it. I believe mine had some cheapo Denon Cartridge, likely elliptical. Played nice though her Sansui 7000, and B&W DM-302 Speakers.
Sure, I went through the whole table for her, top to bottom.
Crackling can be more than just a dirty stylus, one has to run down the line by process of elimination, do the checks, and go from there. Cabling, etc etc to pinpoint the cause.
And often VTF can be an issue. I once installed a brand new $3,000 ZYX Airy 3 on my VPI Table, was so anal with everything, but had initial issues. Sibilance. Tony Benett sounded drunk! LOL
Only one setting I screwed up, I stupidly set VTF too light to 1.7g, and factory suggested setting was 2g.
Just an easy change of ,3g made an entire world of difference. After some further eyes and ears, and listening, I came to realize I had bought one killer cartridge with performance that was so startling, I then knew where the money I spent went! Wow!
Your table is a decent entry level table, easy to live with, I liked it, was easy to work on, reliable, and sounded just fine. I would say one of the Table's biggest weaknesses was it was a bit more prone to some acoustic vibration and definitely helped to have it on a good table-base.
I still have 2 other Denon Tables, both DP-2550. These are of course much better tables, but the DP-30L would/could benefit with some worthy entry level Audio Technica-Denon-etc MM Cartridge, it could be a pretty good performer,