Oli leaking from front of engine

After doing some heavy slashing, on my TEA20, I noticed that there was a lot of oil round the crankshaft pulley.
So I assume the front engine seal has gone.
How hard is it to replace?
Is it a full strip down or can I get it out from just removing the pulley?
Ta, John

Your going to have to pull the front cover. The rope seal, I believe, is stuffed in from behind. A simple look
will tell you. If you don't see a seal edge on the front...You get to pull the cover. Mind you, when you replace
the rope seal, stuff all of it in there. Don't cut it off. If you cut it, you will be afforded the opportunity
to do it again.

Front crankshaft Oil Seal on my TEA 20 is a LIP TYPE SEAL:

Pull the front cover and do yourself a big favor and check the timing gears and chain:

Info you may need:

The Governor weights were ready to fall off/detach from the holding pins. Chain, Sprockets, Governor ,Gaskets, Front oil seal were replaced at sometime in 1967> 1969 when a MAJOR was done to the ENGINE. I rotated the crankshaft CW/CCW and noticed 4 TEETH on the FLYWHEEL had to move before the DISTRIBUTOR ROTOR would move. Now only one tooth on the flywheel will pass before the Rotor moves. The governor was sticking at full throttle and would not idle down.

Info I compiled when REPLACING Crank sprocket ,Camsprocket and Timing Chain.
(1) 85 MM Bore Engine:

(2) Front Lip Oil Seal "National /Federal Mogul Lip Seal" # 472164V A SMALL amount of BLUE Silicone was placed around the inside bore of the front timing chain cover before Lip seal was installed:

(3) I installed a repair SLEEVE on the front drive Pulley, make "DURA SLEEVE" # 99175. The sealing area were the LIP SEAL makes contact was slightly grooved. Dura Sleeve specs. 1.745">1.753" Diam. # 68 Rockwell Hardness:

(4) On installation the Governor plunger shall be reseeded tight against the Flyweights and no weights shall be loose or hanging down:

(5) A small amount (only enough to make the surface shiny) of engine oil was added to the shaft of the governor PLUNGER as well as the timing chain:

(6)There are NO timing MARKES on the NEW Sprockets. You may whish to line the timing marks up (facing each other) before you remove the sprockets:

(7)Place the old sprocket (CAM SPROCKET) on top of the new sprockets and accurately scribe the new sprockets as to the timing marks. There are FOUR hols in the hub of the CAM SPROCKET. Keeping turning the old sprocket until the four hols and all teeth line up. These hols are slightly off set. I used several SHOULDERED cap screws to ensure I had the new and old sprockets properly aligned. You may have to flip the old sprocket over...see right up:

(8) It's good practise to measure the thickness of the hub of the old crankshaft sprocket and the new crankshaft sprocket as the teeth on the two sprockets should align for both proper operation and longevity.(there were shims between the old Crankshaft sprocket and the shoulder portion of the crankshaft):

Cheers
Bob...