Thanks Red1, I see we have a previous thread on this model:
https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=20618In that instance the only problem was a worn out and well-cooked transmission drive belt. Maalste said his belt is fine, but he hasn't yet been back to tell us what kind of hydrostatic transmission is fitted. From our previous thread, I think it was a Tecumseh Peerless VST 705. This transmission was designed as a throw-away, and is not covered by the normal Tecumseh/Peerless workshop manuals. I understand it was sold primarily in Europe.
Maalste, the most common cause of the problem you reported is a slipping belt, and you need to check that by the recommended procedure. It is also possible that the problem is low fluid level, especially if it shows any signs of a transmission fluid leak. The fluid can be topped up, though this is not a normal service procedure, and involves removing the transmission. To get a quick introduction, I suggest you go to this site and check Post 14, where you can read the Peerless service tip on the subject:
http://www.mytractorforum.com/showthread.php?t=156991To do the job more thoroughly, I suggest you download the Tecumseh Service Dealers' and Technicians' Training and Informational Series document here:
http://www.google.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&ved=0CFYQFjAI&url=http%3A%2F%2Fwww.mymowerparts.com%2Fpdf%2FTecumseh-Service-and-Repair-Manuals%2FTECUMSEH-QUICK-REFERENCE-AND-TROUBLESHOOTING-FOR-ENGINES-AND-TRANSMISSIONS-695933.pdf&ei=llW0VKDYEMXo8AXI9YLIBw&usg=AFQjCNGxEMNgNT7eIcR24SF1aThi3ivW2Q&sig2=qd3DFuxxjX6uz01oBMorEw&bvm=bv.83339334,d.dGc
It runs to 94 pages, but you can short-circuit looking at most of this by searching VST entries, using Acrobat.