Sawmill Head Won’t Go Up

[T4R11]

Greetings, I have a Timber Harvester 36HT25 and and my sawmill head won't lift up. The gear box is a Motovario 0065922 with a gear ratio of 20:1. The input shaft is driven by an Eaton hydraulic motor and between the two are to small sprockets with chains. When I try and raise the head, the small sprockets and chains just spin. The previous owner told me when I bought it (now a few years ago) that the gearbox had been rebuilt. A few questions...

1. Is this likely a gear box problem or could it be something else?
2. If it is the gearbox, any advice as to what needs to be disconnected and in what order to get the gear box off?
3. Anyone know of a good gear box repair company?
4. Any other advice or insights welcome.

[barbender]

 Well, if the shaft is spinning where it goes into the gearbox I'd guess your problem is inside it. 

 I'm not familiar with your model of mill, but I would imagine that you will have to blick or chain the head up so you can remove the gearbox.

[Southside]

Can you see if there is a key stock in the shaft that connects the sprocket to the shaft? 

Securing the head and removing the gearbox, or at least opening it up will answer a lot of questions.

[Peter Drouin]

That was the first thing I thought of. keyway moved.

[T4R11]

Thanks for the comments. 

I checked the gear box input shaft, as well as the two small sprocket's with chains on them coming from the hydraulic motor. There are multiple keyways and all appear in order with collars and keys. 

The output shafts, one on each side of the gear box, have collars, both have keyways but no keys. I am not sure if keys are supposed to be there or in the absence of the keys whether this could be the problem. Odd both sides don't have keys. 

Given the previous owner had the gear box rebuilt I wonder if the problem is in the box. I recall reading somewhere that the gear box lubricant is often not added to lessen the cost of shipping. This may be a stretch but I wonder if there is any lubricant in it. I may need to pull it all apart  as a next step.