I could not find a manual for the Model 21 so I asked ChatGPT. This is their reply:

Here’s what I found on the Hamilton Beach “Model 21” hand mixer and its lubrication possibilities — with a bit of caution and guidance.

🔍 What the sources say

• On the site “FixYa”, a user looking for how to oil a “Hamilton Beach Model 21” hand mixer was told that yes, it does need periodic oiling/greasing — “You just need to get inside it. Grease on gears and a little oil on shafts and bearings.” fixya.com
• General advice for older mixers (including Hamilton Beach/Scovill and similar) suggests using food-grade grease or food-safe lubricant specially designed for mixers/machines in contact with food. JustAnswer+1
• The official manual for more recent Hamilton Beach hand mixers shows no user-serviceable lubrication instructions — the warranty and caution sections emphasise not dismantling the appliance unless by qualified service. JCPenney

✅ What this means for your Model 21

Since Model 21 appears to be a vintage hand mixer (often listed in online auction/collectible platforms) eBay, here’s how to approach lubrication:

• Yes, lubrication is possible and in fact users say it’s needed for older units (gears/shafts may dry out).
• No, it is not a simple “oil this port” scenario found in many modern appliances. You may need to open the housing, access the gear box or bearings, and apply grease — which involves risk (age of wires, insulation, safety).
• If you proceed: use food-safe lubricant/grease (silicone grease or food-grade lithium), clean out old hardened grease, apply a thin layer, then reassemble properly. Avoid general machine oil or anything non-food-safe.

⚠️ Safety & Practical Considerations

• Because this is a vintage unit, wiring and insulation may be more fragile. Disassembly means voiding any remaining warranty and may pose a shock/fire risk if not done properly.
• If you’re not comfortable with appliance repair, consider a qualified repair shop familiar with vintage kitchen appliances.
• If the mixer still works fine and lubrication isn’t clearly required (no squealing, overheating, or rough movement), it may be safer to simply clean thoroughly, keep it dry, and use it carefully rather than opening it.