Solution Summary:
Have a can of compressed air and a small flash light nearby
Pre-heat, load starting filament (if using an AMS) and clean nozzle and wipe thoroughly
Clean / blow any debris off of the bed and in / around chamber
I have been meaning to share a few steps I perform with my X1C each time I start a print. I know that these steps may seem obvious to some, but after coming from PRUSA MK3 printers, there are more things to learn and nuances to understand.
I’ve had plenty of assumptions using Bambu, and I know Bambu tried to make this unit more “appliance-like” that anyone can use - but that simply is not the case when you start experimenting with different materials and more advanced prints. Including prints where outer walls and bottom surfaces need to be perfect and through-holes are used etc.
The Problem
At times I was getting blobs along my outer walls, or you may get random color filament strands in your prints, or color deposits throughout. This was fixed simply by ensuring the nozzle was super clean. yep, that was it. I was using PETG, which is super sticky, so don’t assume the starting cleaning / wiping procedures are going to take care of this. (sure you may be able to install a mod, but I don’t want to bother with all that)
The material was stuck to the back side of the nozzle, out of my view AND also stuck to the silicon sock along the sides. It is so dark in the chamber (AMS on top blocking more of my light) it was difficult to see. I wish Bambu used more light rails in the chamber.
During printing, these blobs were being deposited in random places along my prints, after troubleshooting all the less obvious things (print settings or filament quality etc) - it was simply a dirty nozzle.
The Solution
Before each print I select the filament (if using an AMS) that will be my starting color / type and load it. Then I HOME my tool head. When the head is in the center of the bed, before it cools completely, I take a soft rag with a little IPA and wipe all around while hot, including the sock. Once free of debris I start my job and closely monitor the actions to make sure there isn’t any oozing or random filament strings along the bed or stuck to the nozzle. I use a flashlight and handheld blower (which is awesome) to ensure there isn’t any debris on the back shelf or bed that the nozzle can pick up when performing its startup procedures.
Performing these simple steps will save you failed prints and much frustration.
I hope this helps and would love to hear what procedures you perform to ensure successful prints.
Even after cleaning / wiping the nozzle multiple times. I was ready to print a bright yellow color. Cleaning the nozzle revealed more black deposits of PETG stuck to my silicone sock and the back of the nozzle.
There is nothing more frustrating than seeing a random colored filament strand or deposit ruin your first layer or solid color print. 
I use this small flashlight for my chamber inspections and this electric blower is super powerful. More powerful then a can of compressed air and does not loose pressure.
Look how nice the sheen and outer wall surface is. This is printed vertically, using Bambu PETG HF Black - mostly default filament profile settings.
Bed 70
Cooling Min and Max fan speed 40%
Overhang Fan Speed 40%
Filament initial layer 230 other layers 260
Support Type: normal
Style: snug
threshold angle: 90 (so just the through hole itself is supported)
