I took the axle out to clean up the bearings inside. After I was done, I greased everything and tried to put the axle back in, but it didn't fit flush with the hub. Is this even repairable, because I can't even remove the cone/dust cap/nut from my axle anymore.

If I was to buy a replacement axle what would I be looking for? The hub is Tec9.

Let's see, It fit before and now it doesn't after being taken apart & re-greased. Guess it's back to the old drawing board and re-assemble it properly ?

Although it does appear to be worn out. LBS should have a replacement part. What do the bearings look like ? Those might be ground up too and putting it back in/together would only grind up the new parts within a short time. Is that a front or rear hub ?

Just curious, how long did that last ? I have Tec 9's on the Vilano I bought and just curious the lifespan yours had. Mine hasn't given any problems in a year and 11 months.

Bearings are ok and it is a rear hub. I bought this bike used a week ago so I've no idea how long it's been, but judging by the color of the grease when I first disassembled it, I'd say it's either been a while or the previous owner did a piss poor job of maintaining the hub. I've solved the problem by getting a rear axle from my Walmart p.o.s. mountain bike and using that instead.

Although I'm still interested in what kind of axle could serve as a replacement.

To replace an axle,you need to measure the length, the diameter and the thread pitch.

Then consult a purchasing chart, like the one found here for a proper replacement axle.

Loose screws is also another good source for axles:https://www.loosescrews.com/index.cgi

Whatever bolt and other parts that they are from even a WalMart mountain bike hub, are replacement parts. The Tec9 non sealed bearing assembly is nothing special, which is good and bad. Good that it's a commonly found, inexpensive and easily replaced part. Bad that it isn't the highest end hub on the market. Like you said, regrease it periodically and it lasts longer. Where I bought the bike I have and they sell parts if you want to replace them with identical parts.

https://www.bikepartsmart.com/feature...set-white.html
https://www.bikepartsmart.com/feature...ubs-white.html

https://www.tec9components.com/