HOBART D 300,SERIAL NR. 94.819 808, ML NR.116 12

That's a bargain if it works. Apparently the date is hidden in the last three digits of the serial number, so February 1998 seems likely. The only sure way is to contact Hobart themselves. They have a great service department. I have used many Hobart mixers in my catering career.

I found this;

As the previous poster mentions, you can't decipher Hobart serial or ML numbers. I have about 30 pieces of Hobart equipment ranging from mixers to slicers to reach-ins to dishwashers and I couldn't make heads or tails of the numbers. Finally, I got hold of someone at Hobart who I emailed all the model numbers, serial numbers and ML numbers to and they emailed me back the month and year of manufacture. Even after I got the information, I still couldn't figure out where in the serial and ML numbers the manufacture dates were buried.

Sounds like the keys in the shifting sleeve may be sheared. The transmission will have to be disassembled and checked for broken parts. Check www.hobartservice.com for your local Hobart office.

Check that the gear on the shaft that the clutch gear engages with does nort have a sheared key.

SDBARBAS - You might try using the very easy "Hobart" smartparts webapp on the Hobart website. Cut and paste this into your browser Address line: http://catserv1.itwfeg.com/Hobart-Root/items.cfm, which is the parts list and an exploded view of the assembly for: Planetary, Tumbler and Agitator Shaft Unit Assembly. Go to Item # 64, and select "Add". The screen will change to 'Parts Selected'. Increase Qty to 4, hit "Update Quantities" and then hit "Confirm Parts Selected". On the next screen, select "Find Service Office", and follow the instructions on that pop-up window. You should be able to find a Hobart Service Office in your area that can price out your 4 tumbler yoke and shifter pin assembly. Good Luck... I hope this is helpful.

The symptoms you are describing would lead me to believe that the shifter clutch sleeve (part # 70035-1) is worn out. There's a chance that the gear that engages the clutch is worn as well, but less likely. A significant amount of transmission disassembly is required to access and replace these particular parts. There are a lot of things that can go poorly if you don't pay attention to detail when disassembling/reassembeling the transmission of a D300 (ie clutch rollers and springs) On a brighter note, it's about a 90 minute job for a proficient technician, if everything goes his/her way. That money would be well spent.

You may have a wire not fully seated in your plug, or the worm gear you've just replaced is bound by something ( a gear tooth?) or wrong worm gear. Check to see if all the gears are seated properly. You should be able to turn the agitator by hand. If not, something is jammed in the gears. The other possibility is the windings in the armature are bad.

you do not say what model mixer you have but more than likely the shifter yoke is faulty

This is common there is a key on the shifter shaft and when you removed it the key came out and is floating in the grease in the tranny ready to destory the gears. That are no longer available at Hobart. if you want the shifter /switch plate off, remove the pin in shifter and the handle thats all. Hobart has a special puller I have two of them but you can use a H type puller to get to the pull threaded holes Mixer should be upside down on head to repair trans.

Thats the center shaft and if it moves back and forth the lower bearing is bad or the shaft has cracked.You need to remove all 3 shaft assemblys. if you already removed the gears on the center shaft then you need to remove the shifting yoke---turn power off to machine then take the screws off the trim plate where you shift speeds,you might see a switch that sits up on the shifter cam,remove the screws and put switch aside,take the 4 allen screws off and pull on the shifter(it will come out).If you didnt already drain the oil do it before you mess with the shifter.after the shifter is out grab the upper left gear assy. and the gear assy. below it,rock both gear assy. and pull up,they will both come out(you might need some force)once out remove the remaining gears on the center shaft and remove the shifting yokes.you then need to remove the planetary (lower part of mixer)if not already done,then pull the shaft out from the bottom.any questions let me know.

goto this site http://www.hobartcorp.com/default.aspx. you will find a parts list/view. before ordering any parts i would call your local hobart branch because the part numbers have changed.make sure you have the ml number or spec number found on the data plate before hand so youll get the right part numbers.any questions let me know,i repair alot of these mixers im a hobart service tech.