Suzuki DT 4 Outboard- Will not transmit more than 10% power to the propellor

I have a Suzuki $hp outboard that I use on my Zodiac dinghy for my sailboat. At the end of last season the engine would not transmit more than about 10% power to the propellor. The handle turns the accelarator over at full revs- but the engine just revs at full volume - of both noise and power- but very little power is transferred. I have checked the rubber splinds in the propellor and the pin and both are ok- A friend examined the inside of the motor for me but could come up with no solution. I was wondering if anyone had any idea what the problem may be and how I fault diagnose to get the fix in so I can run the engine again- I have been variously advised it amy be a " dog clutch"? problem or a transmission problem? I don't have a manual yet? Are there any online I can access please? Many thanks if you can help.

Model # is.--------Sure sounds like a problem with the propeller.------------Mark the outside of the prop and the hub.---------Test run it and see if marks are still in the same place.------------Is this a problem that developed suddenly or did it gradually get worse ?

Racerone- Thank you for your reply. I will try marking the propellor and the mounting and seeing if they remain in place. The rubber seal with splinds is seemingly in good condition. The recessed pin holding the unit together is slightly bent at both ends but still fits into the recess. There are two new pins in the engine housing- so I can replace and use one. The engine serial number is 00402 - 355737 and it is a DT $ Suzuki. I would be very pleased if it is just the prop- I am a novice when it comes down to opening the engine up and fault finding. Thanks again.

Sorry it's DT4

Is this a problem that developed suddenly ????????

Yes- The engine was running fine at full speed and al speeds in between...then it just suddenly went to 5-10% of power and has remained that way. A friend looked at thge transmission.... put new oil in and then re-assembled it...but the next tim eout it was dangerously low on power in a high wind so I abandoned using it until it's repaired?
Thanks again for reply# 2.

Racerone- Thank you for your suggestion. OI marked the prop and the bushing/housing and they were different places after I ran the engine. So I investigated more closely and placed the rubber splinds in a vice...I turned the housing...it was impossible to tell or see otherwise- but the splinds moved independently of the busing case...and then they came away...so the splinds had perished and this was, as you said the cause of the prop not spinning properly. I have ordered the part - 58120-98600 which appears to be common to all DT 4's and will let you know once it is fixed and runnning. Many thanks for your suggestions it really helped.