A 'poor soil' and 'over-watering' are so closely related they're nearly synonymous, and so prevalent that if you rubber stamped every problem people come here seeking resolution for (plants in pots) you'd probably be right at least 90% of the time. The single issue affecting more growers than even poor light is a poor soil, and 'Black Gold' falls into that category because of its excessive water retention.
Even though now is a poor time of year to be messing with the plant's roots, I agree you should inspect the root system and prune any dead/slimy/shriveled roots back to sound tissue. It would be helpful to dust the roots with flowers of sulfur, as a fungicide. Repot it into the pot it was in originally. Insert a wick into the drain hole and leave it dangle below the pot after each watering. This will drain a LOT of excess water away from the roots. The gravel doesn't work. (See the first and second illustration in the first picture below.) If the soil supports 5" of perched water, the water will simply perch in the soil 5" above the ht of the gravel, so the level of perched water, instead of being 5", will be 5" + the ht of the "drainage layer". If you have 2" of gravel at the bottom, the ht of soggy soil in the pot will be 7" above the pot bottom, for soils that support 5" of perched water - a good guess for Black Gold.
You can also drain a lot of excess water by holding your pot over the sink after watering and moving it downward, then reversing the direction sharply upward. The water in the pot will want to keep moving downward after you reverse directions (see Newton's first law of motion) and will exit the drain. This works if the pot is small enough. Also, tilting the pot after watering can make a significant difference in how much water remains in the pot. See B vs A in the second picture below. Also note illustration E, which shows how much excess water can be removed by using a wick. These tips allow you to use soils that would otherwise be extremely limiting because they hold too much water and insufficient O2.
Learning how to keep a root system happy is the largest single step forward a container gardener can make. A healthy plant is little more than wishful thinking if you can't keep the root system happy. Let me know if you want to learn more about soils that make for happy roots.
Al
