First, get the right pull cord from your parts supplier. It may have originally had a crimped end on in instead of just a knot(?). If your engine is tough to turn over merely due to the compression, loosen your glow plug a little when you start it. As soon as it fires, tighten it back up. If your chassis provides a hole to access the flywheel, you may want to invest in a starter box. They are a great tool, but quite pricey!

Hope this helps,

FP