The original cutter blocks are one-piece forged steel blocks with two spiral cutters which need to be ground in situ on a spiral jig (that jig actually rotates the block as you pull the block across a cup grinding wheel secured at the end of the planer tool shaft). Later cutter blocks had two spiral twist tungsten carbide blades brazed onto the steel block. You can just see one (badly abused) block mounted on the sharpening jig in my photo. These blocks have been unavailable for more than a decade and I have been quoted £100 a pop to have copies manufactured in China, in batches of 25 (best UK price wasvobmver £200). This is not going to happen. Fortunately I managed to buy three brand new blocks when I was in the USA about 20 years ago, but TBH I am seriously considering converting the planer to use a spiral segmented TC-RT cutterblock. I have already done a similar conversion on my current Makita DKP181 (cordless) and the planed surfaces are like glass.
The EHL65 produces a beautiful surface, but those special spiral cutters are stupid money, at least for me, at c. £16/17 a pop. Conventional straight carbide cutters cost me about £19 for 10 (German), £13 for 10 (Chinese), from my regular supplier and are reversible, giving twice the life of a Festool non-reversible spiral blade. This means that for another £1 to £2 over the price of an EHL65 blade I get 20 cutting edges (or just under £1 per edge). Bear in mind that some modern corded planers, like the Bosch blue models, sre single bladed. The downside is that straight blades always leave scallop marks, although that can be sanded out or taken off with a finely set sharp block plane. I used to use an EHL65 at one time, but so many new manufactured doors I needed to adjust came in with staples just below the surface, that I eventually gave up and bought a Bosch GHO31-82 and went back to sanding/hand planing at the end because I simply couldn't justify the replacement cutter cost every time I nicked a blade.
I recently switched cordless planers from a Makita DKP180 brushed model to a DKP181 brushless model (more power and can work rebates) but I also decided to spring for a Sheertak segmented replaceable carbide tip spiral cutter block (which cost almost as much as the planer did). It is brilliant , delivering scallop free, glass smooth surfaces. Well up to Festool standards. Sheertak do a number of spiral TC-RT blocks for cordless and corded power planers, and it's one of those I'm considering for the old Porta-plane, now that it has new bearings and brushes, and that I've sourced the missing screws for it.
Not to certain about how to strip an EHL65, though - I've never had to do it.
I seem to recall there is a knack of removing the front body off the DS140 (something like a left hand threaded locking ring which requires an adjustable C-wrench, but I may well be wrong on that as it's been a couple of decades since I stripped one), but once that is off the motor unit is fundamentally just a paddle switch angle grinder. The main issues are probably brushes, bearings, flex, the switch and the gearbox needing cleaning out and repacking with lithium grease as they are relatively straightforward tools
