I've been following various discussions on this machine, as well as the Bosco group it is associated with (not the modified one used by Bosco, but the generic one used by manufacturers such as Profitec and Londinium). I recall Paul Pratt starting a thread in which he asked people's opinions on this group, stating that he was largely unimpressed with it - apologies if I misunderstood this. These comments stood out for me in light of some ongoing issues I have been having with my Profitec Pro 800. The first issue is documented in an earlier thread I posted, in which I pointed out that a large gap on one side of the upper group, where the cam is joined to the housing via a hex bolt, was causing the cam to rub against the housing when the lever was engaged. In response, Profitec sent me a new upper group. However, after installing this new one, I noticed that distinctively loud "groan" associated with spring rub. Sure enough, when I removed the upper housing to re-lube the bore (to try and reduce the noise) I could see which coils were rubbing against the bore. I tried using a screw driver to re position the spring, but quickly learned that this is practically impossible with double spring versions of this group. I also tried wrapping the affected coils with plumbers tape (as one ingenious HB'er had done) but it only lasted three pulls before the tape rubbed off (maybe not enough winds?). All this is to say that I am now 2 for 2 with this machine, having received two groups with quality control issues. My experience has led me to conclude that Profitec builds great machines, but the weakest link are the groups that they bolt onto them. So, I would agree with Paul's conclusion.

Having said all that, I have a couple of questions I'm hoping some of you can answer. 1) Is the spring/rub noise a normal occurrence with these groups, and if so, does it cause any long term damage, or is it simply an annoying noise that you get used to? and 2) Is there a way to re-align double spring versions of this group so that the noise/rubbing is reduced? (I have read practically everything on this subject on this site, but most seem to involve the single spring Londinium variant.

Signed "frustrated in Calgary"

Ok - forget the first part of the post (upon reflection, it has probably been done to death already). Let me just ask if anyone has ever managed to re position the spring on a double spring version of this group? Using a screw driver did not seem to work for me, as the spring was just too stiff. Thanks in advance!

Ask Fotondrive... I think he was able to reposition his spring, although it was a single spring Londinium I, if I recall correctly. Have you thought about throwing together some parts to make a spring decompressor so you can re align it yourself? If not, maybe someone here has a compressor he can loan you... shouldn't be too hard to make, though. some sturdy wood blocks and some thick threaded rod? I made a compressor years ago for McPherson cartridge type shocks, but I'm not sure what kind of access your spring has. if all else fails, check amazon for McPherson spring shock compressor... I remember seeing them a little while ago, like dirt cheap.

The spring rub issue due to spring buckling/bowing under compression was previously postulated to be the result of the upper and lower spring seats not being parallel throughout the stroke and/or spring end turns not being ground parallel. These types of misalignment can be corrected by remachining the spring seats and/or repositioning the spring slightly. The cause of this in many cases is the manufacturing tolerances accumulating all in the unfavorable direction. The quick check for a manufacturing issue would be to verify that the lower spring seat is at 90 degrees to the piston rod through 360 degrees of rotation and that the piston rod was not bowed.

Automotive valve springs have this problem and the usual fix is the use of 2 counter wound springs per valve or a center spring guide.