Vinegar flies
These tiny, annoying flies indicate acidity. Usually due to excess food (especially fruit/sugar) rotting before your worms can eat it. Only feed worms as much as they are eating, chop up or blend food scraps, and don't let it build up more than 3-5 cm.
Stir through plenty of dry garden scraps and air, then cover your worms with a worm blanket, old cloth, shirt, towel or damp newspaper.
Place a small bowl of old wine or vinegar and a few squirts of dish soap next to your Subpod overnight. This will attract and trap the vinigar flies.
Smells
Tangy smells mean acidity, usually due to anearobic conditions due to over feeding and not enough aeration. Stir through plenty of dry garden scraps and aerate deeply. Sprinkle a table spoon of ash or dolomite or baking soda.
Putrid smells are from excess animal products. Remove if possible, or cover up with a little soil. Be more cautious with animal products in the future.
Boggy smells mean not enough air. Stir through dry garden scraps. Check drainage around your subpod. Relocate if it is in a flooded low lying area. If in heavy clay, replace with potting mix.
Slow worms
Check that you still have plenty of living worms. Worms may not eat mouldy food, so you may need to take it out. Only feed your Subpod as much as your worms can eat. Give them time to breed, then gradually start feeding them more. Add more worms if needed. Note worms naturally slow down in winter.
Ants or cockroaches
Ants or cockroaches indicate your Subpod is too dry. Water your Subpod with a hose or large watering can then gently stir to chase them out without hurting the worms. Keep you Subpod moister and more stirred ongoing. Consider reducing dry garden scraps, especially large items like broad leaves, twigs and bark. Remember to include old tea, drinks and rinse water from your scraps container.
Maggots
This usually means your Subpod got more meat or dairy than it was ready for. Remove any offending items if possible. Stir in and lightly bury magotted areas. Be more careful with animal products in the future!
Mice
Stop feeding your worms for a week and just add wet newspaper. Check there are no holes allowing mice to get in. Peppermint oil and coffee grounds outside of the Subpod may deter vermin. Try adding extra coffee grounds to your Subpod, and avoid grains and meat for a time.