If it looks like the pic, and you have a HPI Nitro Star engine, you have either a K4.6 or a K5.9 engine.
The F4.6 and F5.9 engines have external hex shaped OWB arrangements - which you have said is incorrect for your engine.
Watch out for the spring (and pin?) that fit inside the crankshaft where the pin on the OWB unit fits into.
It's been a while, but I seem to remember small stuff wanting to jump out.
If you have a K4.6. the HPI part number is 15233.
If you have a K5.9, the HPI part number is 15294.
Both discontinued.
Good luck finding one for the 5.9. Someone was asking $95.00 for the last one I saw.
15233 is currently easier to find and at a more reasonable price too.
...can I just replace the bearing its self . Thanks
If cleaning and then applying a drop of one-way bearing lube/oil does not work...
It is possible to replace just the OWB bearing.
Measure the shaft - most I've seen are 6mm - OWB part # HF 0612.
I personally would avoid the knockoffs and buy the one marked HF 0612 and made in Germany.
You have to push the old one out and push the new one in.
I gave it a half-hearted try on a 12mm hex unit but was unsuccessful.
Juice just wasn't worth the squeeze - but then, the 12mm hex is easy to find.